Is there a similar library to FreeMarker like in Java
Hello, I want to do a small project but I need a text replacement tool/lib like Apache's FreeMarker. Is there something similar for D? Thx
Re: preset counter variable in a for loop
On Friday, 28 February 2020 at 12:48:17 UTC, mipri wrote:
On Friday, 28 February 2020 at 12:44:52 UTC, Namal wrote:
Hello,
I don't understand why this simple code causes a compiler
error..
import std.stdio;
void main(){
int b = 0;
for (b; b<3; b++){
writeln(b);
}
}
$Error: b has no effect
Well, that's the error. b has no effect, so there's
no need for it, and it's likely written in error. It
has no effect in C++ either, and you may get a warning:
example.cc: In function 'int main()':
example.cc:7:8: warning: statement has no effect
[-Wunused-value]
for (b; b<3; b++){
Thanks, I didn't know that you don't need it there and can leave
it out!
preset counter variable in a for loop
Hello,
I don't understand why this simple code causes a compiler error..
import std.stdio;
void main(){
int b = 0;
for (b; b<3; b++){
writeln(b);
}
}
$Error: b has no effect
Same works perfectly fine in C++
#include
int main(){
int i = 0;
for(i; i<3; i++)
std::cout<
preset counter variable in a for loop --> 'has no effect' Error
Hello,
I don't understand why this simple code causes a compiler error..
import std.stdio;
void main(){
int b = 0;
for (b; b<3; b++){
writeln(b);
}
}
$Error: b has no effect
Same works perfectly fine in C++
#include
int main(){
int i = 0;
for(i; i<3; i++)
std::cout<
Re: Question about the $ sign in arrays and strings
oooh... I used str = std.readln(); to get my string and there must have been some other sign, line break or whitespace or something at the end :( Now I understand it, thx
Question about the $ sign in arrays and strings
Hello, I wanted to remove the lastchar in a string and figured that you can do that wit str = str[0..$-2]; but why is str = str[0..$] and str=str[0..$-1] the same ?
How to remove whitespace from a string
Hello, what is the way to remove whitespace from a string (not only at the beginning and end)..
User input
Is there any other way to do a simple user input into integer variables without using std.conv?
Re: sorting a string
On Friday, 14 July 2017 at 17:23:41 UTC, Steven Schveighoffer wrote: import std.string: representation, assumeUTF; import std.algorithm: sort; auto bytes = line.representation.dup; bytes.sort; auto result = bytes.assumeUTF; // result is now char[] Why does it have to be char[]? auto bytes = line.representation.dup; bytes.sort; string result = bytes.assumeUTF; works too.
Re: sorting a string
On Friday, 14 July 2017 at 16:43:42 UTC, Anton Fediushin wrote: On Friday, 14 July 2017 at 15:56:49 UTC, Namal wrote: Thx Steve! By sorting string I mean a function or series of functions that sorts a string by ASCII code, "cabA" to "Aabc" for instance. import std.algorithm : sort; import std.stdio : writeln; "cabA".dup.sort.writeln; `dup` is used, because string cannot be modified, so a copy of string used instead. Thx alot. One final question. If I do it like that. I get a deprrecation warning: use std.algorithm.sort instead of .sort property Wasn't .sort() the proper way to use it, no? Because that won't compile.
Re: sorting a string
On Friday, 14 July 2017 at 15:15:42 UTC, Steven Schveighoffer wrote: import std.algorithm: filter; import std.uni: isWhite; line.filter!(c => !c.isWhite).to!string; be warned, this is going to be a bit slow, but that's the cost of autodecoding. If you are looking for just removing ascii whitespace, you can do it a bit more efficiently, but it's not easy. About the string sorting, you'd have to be more specific. -Steve Thx Steve! By sorting string I mean a function or series of functions that sorts a string by ASCII code, "cabA" to "Aabc" for instance.
sorting a string
Is there a 'easy' way to sort a string in D like it is possible
in Python? Also how can I remove whitespace between characters if
I am reading a line from a file and safe it as a string?
string[] buffer;
foreach (line ; File("test.txt").byLine)
buffer ~= line.to!string;
Help me fix my compiler
Hello, I used the Install Script command line to install the newest dmd compiler (Ubuntu 16.04.2 LTS). Now I have to type 'source ~/dlang/dmd-2.074.1/activate' before I can use it and it is also not show in the software center like it used to be. How can I fix it or how can I remove it? Thx
Re: reading from file
Sorry if I wasn't clear. The array should be two demensional and each line in text line should be a row in that 2x2 array.
Re: reading from file
On Tuesday, 13 December 2016 at 16:57:40 UTC, Namal wrote: Sorry if I wasn't clear. The array should be two demensional and each line in text line should be a row in that 2x2 array. Also, it should be saved as an integer.
reading from file
Hello, comming from C++, I find it hard to remember and understand how reading from file should be done in D. Especially since I am not very good in functional programming. So I have a file which looks like this: 1,2,3,4 5,6,7,8 9,11,11,12 and so on How could I read it row by row and create an array accordingly without reading the comma?
Re: How to set array length for multidimensional static arrays
Sorry guys that I didn't express myself well. I also mixed some stuff up. What I wanted to ask is this, in c++ this is valid int x = 3; int y = 10; int arr [x][y]; x,y are known at the compile time and arr is a static array. I can't do that in D so what is the best way to declare an array of that size?
Re: How to set array length for multidimensional static arrays
On Monday, 1 February 2016 at 12:12:00 UTC, Jonathan M Davis wrote: On Monday, February 01, 2016 11:15:40 Namal via Digitalmars-d-learn wrote: Sorry guys that I didn't express myself well. I also mixed some stuff up. What I wanted to ask is this, in c++ this is valid int x = 3; int y = 10; int arr [x][y]; x,y are known at the compile time and arr is a static array. I can't do that in D so what is the best way to declare an array of that size? If x and y are known at compile time, then you can declare a static array using them for dimensions. e.g. enum x = 3; enum y = 10; int[y][x] arr; But x and y must be something that it is evaluated by the compiler at compile time - e.g. an enum or a static variable. A local variable that just so happens to be directly initialized (like in your example) won't work. If x and y are _not_ known at compile time, then you can't use the to declare a static array. You'll have to use a dynamic array. e.g. auto arr = new int[][](x, y); - Jonathan M Davis Thanks alot, I didn't know that way with new.
Re: How to set array length for multidimensional static arrays
On Monday, 1 February 2016 at 07:41:33 UTC, Namal wrote: I understand that I cannot pass a variable to the static array like in C++, and have to use dynamic arrays. But how can I set the length for them without using a loop? I mean std::vector in C++, not array.
is there a set container?
Hello, I am looking for data structure equivalent to std::set from C++. Couldn't find it in the documentation.
Calling functions from other files/modules
Hello, finally I want to learn how to do it right and I tried to understand it from here https://en.wikibooks.org/wiki/D_(The_Programming_Language)/d2/Modules But I have a few questions. Do I have always to include std.stdio in every file like in the example or is it enough just to import a module which has this already included? Why do I need to define my main as the main module? I can't imagine that I can import it somewhere else. Is there something like #pragma once that needs to be done?
Re: Calling functions from other files/modules
On Wednesday, 6 January 2016 at 22:15:43 UTC, Adam D. Ruppe wrote: You can import it as long as you define it! I just tried to import one module with a main into another, but I get this: Error: only one main allowed
Re: Calling functions from other files/modules
On Wednesday, 6 January 2016 at 23:06:38 UTC, Adam D. Ruppe wrote: On Wednesday, 6 January 2016 at 23:00:43 UTC, Namal wrote: I just tried to import one module with a main into another, but I get this: You can't have two mains, but you can import a module with main from another module without one. How can I produce a program file from that module which has no main but uses some functions from main module?
Re: functional way doing array stuff/ lambda functions
On Sunday, 13 December 2015 at 01:01:07 UTC, cym13 wrote:
That's because you want to modify it in product passing it by
ref.
Hmm, that seems different to c++.
On Sunday, 13 December 2015 at 11:37:50 UTC, cym13 wrote:
As cryptic as it is this means that the range you passed to
reduce is empty. Reduce needs it not to be because as I said it
needs a seed and as you didn't pass one explicitely as argument
it tries to take the first element of the range (and fails
obviously). You can either pass it a seed explicitely or add a
non-empty check before the return.
Here is the full code, where I changed the product function.
Sorry, I don't understand what the difference now and why it
crashes.
import std.stdio, std.array, std.algorithm;
int product(const ref int[] arr){
/*int p = 1;
foreach(i;arr)
p*=i;
return p;*/
return arr.reduce!((a, b) => a*b)();
}
int [] prim_sieve(int n){
bool [] T;
T.length = n;
T[0] = true;
T[1] = true;
for(int i = 2; i*i <= T.length-1;++i){
for(int j = i*i;j1)
v~=n;
return v.dup.sort.uniq.array;
}
void bubblesort(ref int[2][] v){
size_t n = v.length;
do{
int newn = 1;
for(int i = 0;iv[i+1][1]){
auto temp = v[i];
v[i] = v[i+1];
v[i+1] = temp;
newn = i+1;
}
}
n=newn;
}
while(n>1);
}
void main(){
int[] P = prim_sieve(500);
int[2][] v;
foreach(k;1..11){
auto t = prim_factors(k,P);
v~= [k,product(t)];
}
bubblesort(v);
writeln(v[][0]);
}
Re: functional way doing array stuff/ lambda functions
On Saturday, 12 December 2015 at 23:50:55 UTC, Xinok wrote:
On Saturday, 12 December 2015 at 23:36:43 UTC, cym13 wrote:
...
So, in your example:
int product(const ref int[] arr) {
import std.array: array;
import std.algorithm: reduce;
arr = arr.reduce!((p, i) => p*i).array;
}
A good post overall but you got reduce wrong. In D, reduce
computes and returns the result immediately, not a lazy range.
The following code is correct:
int product(const ref int[] arr) {
import std.array: array;
import std.algorithm: reduce;
return arr.reduce!((p, i) => p*i)();
}
Example: http://dpaste.dzfl.pl/fc2c2eab2d02
I tried this, it compiles, but crashes when I try to run it:
object.Exception@/usr/include/dmd/phobos/std/algorithm/iteration.d(2481):
Enforcement failed
??:? pure @safe void
std.exception.bailOut!(Exception).bailOut(immutable(char)[],
ulong, const(char[])) [0x43a547]
??:? pure @safe bool std.exception.enforce!(Exception,
bool).enforce(bool, lazy const(char)[], immutable(char)[], ulong)
[0x43a4c4]
??:? pure @safe int
std.algorithm.iteration.__T6reduceS305ep1247productFKxAiZ9__lambda2Z.reduce!(const(int)[]).reduce(const(int)[]) [0x43a2ed]
??:? int ep124.product(ref const(int[])) [0x439d49]
??:? _Dmain [0x43a229]
??:?
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv
[0x448b9a]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int
function(char[][])*).tryExec(scope void delegate()) [0x448af0]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int
function(char[][])*).runAll() [0x448b56]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int
function(char[][])*).tryExec(scope void delegate()) [0x448af0]
??:? _d_run_main [0x448a4d]
??:? main [0x4447ad]
??:? __libc_start_main [0xd9f09ec4]
Re: functional way doing array stuff/ lambda functions
On Sunday, 13 December 2015 at 00:02:11 UTC, cym13 wrote:
Now that I think about it, it's true that it would make no
sense whatsoever to return a range as reduce is typically used
to return a single value... At least it makes perfect sense.
Thanks alot, this helped alot. But I have another question
I have two functions:
int[] prim_factors(int n, const ref int[] P){
int[] v;
for(int i; P[i]*P[i]<=n;++i){
while(n%P[i]==0){
v~=P[i];
n/=P[i];
}
}
if(n>1)
v~=n;
return v.dup.sort.uniq.array;
}
int product(const ref int[] arr){
int p = 1;
foreach(i;arr)
p*=i;
return p;
}
While vector P contains some primes I get with a prime sieve. So
if I just try to use those functions like:
writeln(product(prim_factors(10,P)));
I get the error:
function prog.product (ref const(int[]) arr) is not callable
using argument types (int[])
Why do I have to call it like that first:
auto v = prim_factors(10,P);
writeln(product(v));
?
functional way doing array stuff/ lambda functions
Hello guys,
I am still uncertain how to do it right when it comes to lambda
functions. For instance: how do I multiply all the elements in an
array ?
int product(const ref int[] arr){
int p = 1;
foreach(i;arr)
p*=i;
return p;
}
Re: reading file byLine
On Saturday, 7 November 2015 at 17:13:33 UTC, Namal wrote: On Saturday, 5 September 2015 at 14:49:13 UTC, deed wrote: On Saturday, 5 September 2015 at 14:44:19 UTC, deed wrote: .map!(s => chomp(s, "\"") .map!(s => chompPrefix(s, "\"") should be .map!(s => chomp(s, "\"")) .map!(s => chompPrefix(s, "\"")) Hello again, Now I have a file that looks like a b c d e f g h I want to get that in an element of strings but without quatation marks auto a = f.byLine() .map!(a => a.split) .array(); f.close(); Sorry for double post, I pressed accidently 'enter'. How can I ad chomp so the quatation marks are removed?
Re: reading file byLine
On Saturday, 5 September 2015 at 14:49:13 UTC, deed wrote: On Saturday, 5 September 2015 at 14:44:19 UTC, deed wrote: .map!(s => chomp(s, "\"") .map!(s => chompPrefix(s, "\"") should be .map!(s => chomp(s, "\"")) .map!(s => chompPrefix(s, "\"")) Hello again, Now I have a file that looks like a b c d e f g h I want to get that in an element of strings but without quatation marks auto a = f.byLine() .map!(a => a.split) .array(); f.close();
Re: conver BigInt to string
On Thursday, 5 November 2015 at 17:40:12 UTC, bearophile wrote:
Namal:
Hello I am trying to convert BigInt to string like that while
trying to sort it:
void main() {
import std.stdio, std.algorithm, std.conv, std.bigint,
std.string;
auto n = 17.BigInt ^^ 179;
n.text.dup.representation.sort().release.assumeUTF.writeln;
}
Bye,
bearophile
can I import libraries anywhere? Is this the proper way to do so?
Re: conver BigInt to string
On Thursday, 5 November 2015 at 16:35:01 UTC, BBasile wrote: On Thursday, 5 November 2015 at 16:29:30 UTC, Namal wrote: Hello I am trying to convert BigInt to string like that while trying to sort it: string s1 = to!string(a).dup.sort; and get an error cannot implicitly convert expression (_adSortChar(dup(to(a of type char[] to string what do I do wrong? try ".idup" otherwise "auto s1 = " auto did it, but idup leads to Error: can only sort a mutable array
Re: conver BigInt to string
On Thursday, 5 November 2015 at 17:13:07 UTC, Ilya Yaroshenko wrote: string s1 = to!string(a).dup.sort.idup; well, but I was just told not to use sort ??
Re: conver BigInt to string
On Thursday, 5 November 2015 at 16:45:10 UTC, Meta wrote: On Thursday, 5 November 2015 at 16:29:30 UTC, Namal wrote: Hello I am trying to convert BigInt to string like that while trying to sort it: string s1 = to!string(a).dup.sort; and get an error cannot implicitly convert expression (_adSortChar(dup(to(a of type char[] to string what do I do wrong? Try this instead: string s1 = to!string(a).idup.sort() If I try it like that i get: Error: template std.algorithm.sorting.sort cannot deduce function from argument types !()(char[]), candidates are: /../src/phobos/std/algorithm/sorting.d(996):
conver BigInt to string
Hello I am trying to convert BigInt to string like that while trying to sort it: string s1 = to!string(a).dup.sort; and get an error cannot implicitly convert expression (_adSortChar(dup(to(a of type char[] to string what do I do wrong?
Re: How to detect overflow
On Wednesday, 4 November 2015 at 07:59:44 UTC, Ali Çehreli wrote:
On 11/03/2015 11:52 PM, Namal wrote:
http://dlang.org/phobos/core_checkedint.html
It says:
"The overflow is sticky, meaning a sequence of operations can
be done
and overflow need only be checked at the end."
But how can I make multiple operations? I can only put 2
values in the
function.
import core.checkedint;
void main() {
bool overflowed;
auto result = adds(int.max, 1, overflowed); // this
overflows
adds(1, 2, overflowed); // this does not reset the flag
assert(overflowed);
}
Ali
wow, this I don't understand at all, how do those two operations
connected to each other? By the bool value?
Re: foreach loop
On Tuesday, 3 November 2015 at 14:52:19 UTC, Adam D. Ruppe wrote:
On Tuesday, 3 November 2015 at 14:47:14 UTC, Namal wrote:
I remember it is possible to get the index for each element in
the foreach loop, but I forgot how to do it. Can you help me
out please. Thx.
for many of them it is as simple as:
foreach(index, element; array) { }
Thank you. I am still struggling with the functional ways of D.
Now how could I write this foreach loop the functional way?
bool[] arr = [ture, false, ture, ...];
int count;
foreach(i;arr){
if(!i)
count++;
}
writeln(count);
Re: foreach loop
On Tuesday, 3 November 2015 at 15:10:43 UTC, wobbles wrote:
On Tuesday, 3 November 2015 at 15:06:00 UTC, Namal wrote:
On Tuesday, 3 November 2015 at 14:52:19 UTC, Adam D. Ruppe
wrote:
On Tuesday, 3 November 2015 at 14:47:14 UTC, Namal wrote:
I remember it is possible to get the index for each element
in the foreach loop, but I forgot how to do it. Can you help
me out please. Thx.
for many of them it is as simple as:
foreach(index, element; array) { }
Thank you. I am still struggling with the functional ways of
D. Now how could I write this foreach loop the functional way?
bool[] arr = [ture, false, ture, ...];
int count;
foreach(i;arr){
if(!i)
count++;
}
writeln(count);
writefln("Count is: %s", arr
.filter!(a => a==true)
.sum);
// Note: std.algorithm.sum is the same as
// std.algorithm.reduce!((a,b)=a+b);
well I tried this that way, but my count stays 0, same as if I do
it in an int function with a return though I clearly have some
false elements in the arr.
Re: foreach loop
On Tuesday, 3 November 2015 at 15:10:43 UTC, wobbles wrote:
On Tuesday, 3 November 2015 at 15:06:00 UTC, Namal wrote:
On Tuesday, 3 November 2015 at 14:52:19 UTC, Adam D. Ruppe
wrote:
On Tuesday, 3 November 2015 at 14:47:14 UTC, Namal wrote:
I remember it is possible to get the index for each element
in the foreach loop, but I forgot how to do it. Can you help
me out please. Thx.
for many of them it is as simple as:
foreach(index, element; array) { }
Thank you. I am still struggling with the functional ways of
D. Now how could I write this foreach loop the functional way?
bool[] arr = [ture, false, ture, ...];
int count;
foreach(i;arr){
if(!i)
count++;
}
writeln(count);
writefln("Count is: %s", arr
.filter!(a => a==true)
.sum);
// Note: std.algorithm.sum is the same as
// std.algorithm.reduce!((a,b)=a+b);
How do I save sum as integer or something I try;
arr.writeln;
return arr.filter!(a=>a==false).sum;
but I get
[true, false, true, false, true, true, true, false, true, false]
0
How to detect overflow
Is there a way to detect overflow for example for: int i = 2_000_000_000; int a = i*i*i; writeln(a); -> 1073741824
Re: How to detect overflow
On Wednesday, 4 November 2015 at 04:22:03 UTC, BBasile wrote: On Wednesday, 4 November 2015 at 03:55:13 UTC, Namal wrote: Is there a way to detect overflow for example for: int i = 2_000_000_000; int a = i*i*i; writeln(a); -> 1073741824 You can use core.checkedint [1] --- http://dlang.org/phobos/core_checkedint.html It says: "The overflow is sticky, meaning a sequence of operations can be done and overflow need only be checked at the end." But how can I make multiple operations? I can only put 2 values in the function.
Re: How to detect overflow
On Wednesday, 4 November 2015 at 04:22:03 UTC, BBasile wrote: On Wednesday, 4 November 2015 at 03:55:13 UTC, Namal wrote: Is there a way to detect overflow for example for: int i = 2_000_000_000; int a = i*i*i; writeln(a); -> 1073741824 You can use core.checkedint [1] --- http://dlang.org/phobos/core_checkedint.html Is it just an error in the documentation that the return value is stated as sum for the multiplication functions?
Re: foreach loop
Hello guys, I remember it is possible to get the index for each element in the foreach loop, but I forgot how to do it. Can you help me out please. Thx.
foreach loop
Is it possible to create a foreach loop with a breakstetemen? I mean something like that for the second loop where i want to break if element from: int [] g = [9,15,21]; int [] v = [2,3,5,7,8,9,11,13,17,19]; foreach(j;1..10) for(int i = 0; v[i]
Re: foreach loop
On Monday, 19 October 2015 at 14:43:04 UTC, Rikki Cattermole wrote: On 20/10/15 3:28 AM, Namal wrote: Is it possible to create a foreach loop with a breakstetemen? I mean something like that for the second loop where i want to break if element from: int [] g = [9,15,21]; int [] v = [2,3,5,7,8,9,11,13,17,19]; foreach(j;1..10) for(int i = 0; v[i]
Re: foreach loop
Is it possible to use foreach backwards? foreach(int i;20..1) writeln(i); compiles but I get nothing.
Tree datatype
Hello, I don't remember exactly but I think when I first saw D code there was tree datatype implemented without pointers. Is it possible to make a tree struct without pointers?
Re: How to do unittests
On Wednesday, 30 September 2015 at 14:44:20 UTC, qsdf wrote:
On Wednesday, 30 September 2015 at 14:20:28 UTC, Namal wrote:
On Wednesday, 30 September 2015 at 13:03:52 UTC, Rikki
Cattermole wrote:
On 01/10/15 1:59 AM, Namal wrote:
Hello,
can someone give me a complete example please how to do
unittests? I
tried this with the example from german wikipedia, but the
flag
-unittest didn't make any difference.
Example file with loads of unittests:
https://github.com/rikkimax/alphaPhobos/blob/master/source/std/experimental/uri.d
If you were to compile it e.g. dmd uri.d it won't be much use
(unittest wise). You will need to dmd -unittest uri.d to
compile them in. Don't forget to do the same for your main
function. When you run the final executable the tests will
execute before your main function does.
can't I do unittest in the main?
D unit tests are like a stack of free functions. You put them
separatly.
when there's a main: dmd -unittest a.d
--
module a;
void main(){}
unittest{}
--
when there is no main: (like std.uri): dmd -main -unittest a.d
--
module a;
unittest{}
--
the -main switch adds a dummy main function so that the output
can be executed.
But most of the time you'll think that nothing happens because
the tests succeed...
So do I understand it right that it stops after the first failed
test? Is it possible to continue and get a list of all failed
tests?
How to do unittests
Hello, can someone give me a complete example please how to do unittests? I tried this with the example from german wikipedia, but the flag -unittest didn't make any difference.
Re: How to do unittests
On Wednesday, 30 September 2015 at 13:03:52 UTC, Rikki Cattermole wrote: On 01/10/15 1:59 AM, Namal wrote: Hello, can someone give me a complete example please how to do unittests? I tried this with the example from german wikipedia, but the flag -unittest didn't make any difference. Example file with loads of unittests: https://github.com/rikkimax/alphaPhobos/blob/master/source/std/experimental/uri.d If you were to compile it e.g. dmd uri.d it won't be much use (unittest wise). You will need to dmd -unittest uri.d to compile them in. Don't forget to do the same for your main function. When you run the final executable the tests will execute before your main function does. can't I do unittest in the main?
Re: reading file byLine
Hello guys, is there a nice functional way to read the file which is like 1,2,3,4,5,6 2,3,4,5,6,7 8,9,0,9,2,3 line by line, split numbers and remove each ',' convert it to int and save in a matrix int[][] arr?
Re: reading file byLine
On Friday, 18 September 2015 at 10:34:41 UTC, Edwin van Leeuwen
wrote:
On Friday, 18 September 2015 at 10:26:46 UTC, Namal wrote:
Hello guys, is there a nice functional way to read the file
which is like
1,2,3,4,5,6
2,3,4,5,6,7
8,9,0,9,2,3
line by line, split numbers and remove each ','
convert it to int and save in a matrix int[][] arr?
Not tested, but I think the following should work:
auto matrix = str
.byLine
.map!((l) => l.split(",")// Split each line
.map!(to!int) // Turn into ints
.array)// Return an array
.array // Copy into an array
And how do tell here to read my file?
Re: reading file byLine
On Friday, 18 September 2015 at 11:37:15 UTC, Edwin van Leeuwen wrote: On Friday, 18 September 2015 at 11:11:51 UTC, Namal wrote: compiles but crashes For me it works fine. You probably have extra spaces or something in your file. It would help if you posted the error message you get when running the program. Oh, yes, sorry, there was a space after the end of one line
Re: reading file byLine
On Friday, 18 September 2015 at 11:06:46 UTC, Edwin van Leeuwen
wrote:
On Friday, 18 September 2015 at 10:48:25 UTC, Namal wrote:
On Friday, 18 September 2015 at 10:34:41 UTC, Edwin van
Leeuwen wrote:
On Friday, 18 September 2015 at 10:26:46 UTC, Namal wrote:
Hello guys, is there a nice functional way to read the file
which is like
1,2,3,4,5,6
2,3,4,5,6,7
8,9,0,9,2,3
line by line, split numbers and remove each ','
convert it to int and save in a matrix int[][] arr?
Not tested, but I think the following should work:
auto matrix = str
.byLine
.map!((l) => l.split(",")// Split each line
.map!(to!int) // Turn into ints
.array)// Return an array
.array // Copy into an array
And how do tell here to read my file?
Replace str with File("myfile"):
auto matrix = File("myfile")
.byLine
.map!((l) => l.split(",")// Split each line
.map!(to!int) // Turn into ints
.array)// Return an array
.array // Copy into an array
import std.file, std.stdio, std.string, std.conv, std.algorithm,
std.array;
void main(){
auto matrix = File("test.txt")
.byLine
.map!((l) => l.split(",")// Split each line
.map!(to!int) // Turn into ints
.array)// Return an array
.array();
matrix.writeln;
}
compiles but crashes
Re: reading file byLine
So do I understand it right: does => in map! indicates a lambda function?
Re: Why does reverse also flips my other dynamic array?
Why is also b flipped here? This doesn't happen if I use static arrays. nvm. I need to .dup that.
Re: reading file byLine
On Monday, 7 September 2015 at 10:28:20 UTC, deed wrote: On Monday, 7 September 2015 at 10:25:09 UTC, deed wrote: writeln(x);// or you can pass it to a function. I meant `writeln(x + 5)` If I have just red your post before I started using reverse on dynamic arrays... Anyway, there is no .reverse for strings I guess, what is the way to completely reverse a string in D?
Sum and other algorithm functions
Hello, how can I define the range for the sum function which I want to sum up? For instance how do I sum up the first 3 elements of an array int[] a = [1,2,3,4,5,6,7,8,9]; or the last 3?
Re: reading file byLine
On Sunday, 6 September 2015 at 20:39:27 UTC, deed wrote:
On Sunday, 6 September 2015 at 17:57:49 UTC, Namal wrote:
Yeah, I just checked, it is 2.066, how can I install the new
version on ubuntu with sudo apt-get?
sudo apt-get install dmd
will give you dmd v2.067.1. Don't know when it will be upgraded
to 2.068 though.
I used the software center to install the newest one. Now it
compiles but I have no clue how to use uniq properly. I just tried
uniq(sort(arr));
and
auto arr = sort(a).uniq!("a==b").array;
but I don't get an array with unique elements.
Re: reading file byLine
That should be it though... Could you try this minimal complete
test?
import std.stdio;
import std.algorithm;
void main(string[] args) {
int[] arr = [1, 2, 4, 2, 3, 4, 1];
arr.sort.uniq.writeln;
}
// [1, 2, 3, 4]
yes, it works likte that.
unique(arr) I get
Error: undefined identifier 'unique', did you mean template
'uniq(alias pred = "a == b", Range)(Range r) if
(isInputRange!Range && is(typeof(binaryFun!pred(r.front,
r.front)) == bool))'?
Re: reading file byLine
Well, if you don't type function names right, it will be hard to help you. oh, sorry. But I found out what I have been doing wrong besides that. arr.sort.uniq; uniq(arr) or arr.sort.uniq; compiles but doesn't store it in the arr array, I need to store it in a new one.
Re: reading file byLine
Are you on 2.066 or older? Back then std.algorithm hasn't been split into submodules yet. Just import std.algorithm then instead of std.algorithm.comparison, std.algorithm.iteration, etc. Yeah, I just checked, it is 2.066, how can I install the new version on ubuntu with sudo apt-get? I don't realy want to mess with is manually. Also tried just to use algorithm and I get same error message.
Re: reading file byLine
Note that there's a specialized `std.algorithm.iteration.sum`. is there any function that removes double elements in a sorted array?
Re: reading file byLine
On Sunday, 6 September 2015 at 15:52:38 UTC, anonymous wrote: On Sunday, 6 September 2015 at 15:41:34 UTC, Namal wrote: is there any function that removes double elements in a sorted array? std.algorithm.iteration.uniq http://dlang.org/phobos/std_algorithm_iteration.html#uniq Hmm, I get Error: module comparison is in file 'std/algorithm/comparison.d' which cannot be read import path[0] = /usr/include/dmd/phobos import path[1] = /usr/include/dmd/druntime/import when I try to load the headers like in the example
Re: reading file byLine
On Saturday, 5 September 2015 at 18:57:52 UTC, deed wrote:
On Saturday, 5 September 2015 at 17:31:39 UTC, Namal wrote:
Yeah, I have have been trying this example from wiki books
https://en.wikibooks.org/wiki/Learning_D_With_Project_Euler
It is not even compiling.
What exactly is not compiling?
the last codesample on the bottom. I think because of the old D?
Index for the last array.length-1 is now $-1. But also I get
Error: undefined identifier 'file'
for the read line. But even when I fixed those errors the strings
I got were with those quotation marks and backslashes. However,
with your help I could solve it now.
I moved to the next problem and wrote the program for it
import std.stdio, std.algorithm, std.array;
bool abundant(int n){
int[] a;
foreach(i;1..n)
if(!(n%i))
a~=i;
auto sum = reduce!((a,b)=>a+b)(0,a);
return sum>n;
}
void main(){
long sum;
int[] arr;
int[28123] mark;
foreach(i;1..28124)
if(abundant(i))
arr~=i;
foreach(i;arr)
foreach(j;arr){
if(i+j>28123)
break;
mark[i+j-1] = 1;
}
for(auto i = 0;i
Re: reading file byLine
On Saturday, 5 September 2015 at 14:49:13 UTC, deed wrote: On Saturday, 5 September 2015 at 14:44:19 UTC, deed wrote: .map!(s => chomp(s, "\"") .map!(s => chompPrefix(s, "\"") should be .map!(s => chomp(s, "\"")) .map!(s => chompPrefix(s, "\"")) Yeah, I have have been trying this example from wiki books https://en.wikibooks.org/wiki/Learning_D_With_Project_Euler It is not even compiling.
Re: reading file byLine
On Friday, 4 September 2015 at 12:09:19 UTC, Edwin van Leeuwen
wrote:
On Friday, 4 September 2015 at 12:06:08 UTC, Edwin van Leeuwen
wrote:
On Friday, 4 September 2015 at 11:50:23 UTC, deed wrote:
import std.algorithm, std.range, std.array, std.string,
std.stdio,
std.conv;
int[] arr1 = [1, 2, 30];
//arr1.max.writeln; // Doesn't work, as you say
arr1.reduce!max.writeln;// This does. Prints 30.
Again using reduce is the functional way to do it. The above
basically boils down to:
int[] arr1 = [1, 2, 30];
int maxElement = arr1[1];
foreach( element; arr1[2..$] ) //2..$ is short hand for second
till last ($) element
{
maxElement = max( maxElement, element );
}
writeln( maxElement );
Sorry been using too much R, so my indexes are off by 1:
int[] arr1 = [1, 2, 30];
int maxElement = arr1[0];
foreach( element; arr1[1..$] ) //1..$ is short hand for second
till last ($) element
{
maxElement = max( maxElement, element );
}
writeln( maxElement );
Thx guys. Now I try out the split function. I read the file as a
single string?
auto arr = split(cast(string)read(filename),",");
where the file has "A", "B", "C"
and I get the output ["\"A\"", " \"B\"", " \"C\"\n"]
I can understand that read functions reads the endl but what does
it with the quotation marks? how can I modify read so I get just
["A", "B", "C"]
Re: reading file byLine
On Friday, 4 September 2015 at 01:55:13 UTC, deed wrote: On Friday, 4 September 2015 at 01:31:28 UTC, Namal wrote: How can I get just the maximum element? Do I need to give a range for it? Use max? http://dlang.org/phobos/std_algorithm_comparison.html#max Sorry, I don't understand the syntax yet. How do I tell max to search all elements? I mean, why does sort(myarray) is legit and max(myarray) isn't.
Re: reading file byLine
On Wednesday, 2 September 2015 at 22:19:11 UTC, wobbles wrote:
On Wednesday, 2 September 2015 at 21:53:20 UTC, Namal wrote:
Thx guys, this helped alot. The next thing I want to do is
read the file line by line and split the stream into words. I
found this example of code that seems to do sort of something
like it. How can I modyfy it so I can store the words in an
array of strings? Is a => a.length the iterator range?
import std.algorithm, std.stdio, std.string;
// Count words in a file using ranges.
void main()
{
auto file = File("file.txt"); // Open for reading
const wordCount = file.byLine()// Read lines
.map!split // Split into
words
.map!(a => a.length) // Count words
per line
.sum(); // Total word
count
writeln(wordCount);
}
I would do what you want like this
auto file = File("file.txt");
auto words = file.byLine() // you've all lines in
range
.map!(a => a.split); // read each line,
splitting it into words
// now you've a range,
where each element is an array of words
The map!(a => a.split) line simply maps each element to the
return value of a.split - this is the predicate.
The a => a.split syntax is a lambda expression that tells map
what to do on each element.
hello, just copy pasting this brought me those errors:
ep18.d(10): Error: no property 'split' for type 'char[]'
/usr/include/dmd/phobos/std/algorithm.d(427):instantiated
from here: MapResult!(__lambda1, ByLine!(char, char))
ep18.d(10):instantiated from here: map!(ByLine!(char,
char))
and then a long list to the end of my code
Error: undefined identifier a
How to test if a double has no fraction part
Hello, is there a modf function like in C++ or something similar which could help me find out if a double has a fractional part or not. Thx
Re: reading file byLine
Sorry, I didn't notice the "convert all the elements in it to
integer" part.
I think I saw reference to the to! before...that is one way to
convert.
auto words = file.byLine() // you've all lines in
range
.map!(a => a.split)
.map!(a => to!int(a)).array();
import std.file, std.stdio, std.string, std.conv;
void main(){
auto file = File("text.txt");
auto numbers = file.byLine()
.map!(a => a.split)
.map!(a => to!int(a)).array();
writeln(numbers);
}
ep18.d(7): Error: no property 'map' for type 'ByLine!(char, char)'
Re: reading file byLine
On Thursday, 3 September 2015 at 23:54:44 UTC, H. S. Teoh wrote:
On Thu, Sep 03, 2015 at 11:38:54PM +, Namal via
Digitalmars-d-learn wrote:
On Thursday, 3 September 2015 at 23:31:27 UTC, Jordan Wilson
wrote:
>On Thursday, 3 September 2015 at 23:28:37 UTC, Namal wrote:
>>On Thursday, 3 September 2015 at 23:25:52 UTC, Jordan Wilson
>>wrote:
>>>And also:
>>>import std.algorithm
>>>
>>>Sorry, I should have taken the time to answer properly and
>>>fully.
>>
>>import std.file, std.stdio, std.string, std.conv,
>>std.algorithm;
>>
>>void main(){
>>
>>auto file = File("text.txt");
>>auto numbers = file.byLine()
>> .map!(a => a.split)
>> .map!(a => map!(a => to!int(a))(a))
>> .array();
>>
>>writeln(numbers);
>>}
>>
>>Error: no property 'array' for type 'MapResult!(__lambda2,
>>MapResult!(__lambda1, ByLine!(char, char)))'
>>
>>Still an error.
>
>import std.array
Thx, finaly, this is so much harder to understand than c++
iostream
I would have written it slightly differently, to emphasize what
exactly is going on:
auto numbers = File("text.txt") // read file
.byLine() // line by line
.map!(a => a.split // split each line into words
.map!(a => to!int(a)) // convert each word into int
.array) // collect the ints into an array (per
line)
.array; // collect all line arrays into one big
array
This is the functional way of doing it, of course. If you're
more comfortable with the C++-style imperative approach, you
could do this instead:
auto file = File("text.txt");
int[][] numbers;
foreach (line; file.byLine) {
auto words = line.split;
int[] lineNums;
foreach (word; words) {
lineNums ~= word.to!int;
}
numbers ~= lineNums;
}
The functional approach is admittedly a bit harder to
understand at first, but it's extremely powerful because it
processes everything in a pipeline, and you can compose
operators on the pipeline easily, rearrange the sequence of
operations, etc..
In the imperative nested-loop approach, things quickly get out
of hand once the loop is nested about 2-3 levels deep. A nested
loop of 6-7 levels deep would be basically impossible to
understand, maintain, or debug without major refactoring into
smaller functions. (In fact, split() is a library-provided
function that basically encapsulates one of those nested
loops.) But if you take the refactoring to its logical
conclusion, you'll eventually end up with a whole bunch of tiny
functions with only a single loop each, each calling the next
function in a chain -- in other words, you arrive at the
functional pipeline approach. :-)
D allows you to do it either way, but the superior approach IMO
is to learn the functional pipeline approach.
T
Thx Theo, this and the lack of foolproof tutorials were the
reason why I gave up on D 2 years ago and went instead to C++.
But I am not giving up this time. That being said, when do I have
to import std.array and std.string? Every time I use std.array? I
can obviously use arrays and strings without those libs.
Re: reading file byLine
On Thursday, 3 September 2015 at 23:31:27 UTC, Jordan Wilson
wrote:
On Thursday, 3 September 2015 at 23:28:37 UTC, Namal wrote:
On Thursday, 3 September 2015 at 23:25:52 UTC, Jordan Wilson
wrote:
And also:
import std.algorithm
Sorry, I should have taken the time to answer properly and
fully.
import std.file, std.stdio, std.string, std.conv,
std.algorithm;
void main(){
auto file = File("text.txt");
auto numbers = file.byLine()
.map!(a => a.split)
.map!(a => map!(a => to!int(a))(a))
.array();
writeln(numbers);
}
Error: no property 'array' for type 'MapResult!(__lambda2,
MapResult!(__lambda1, ByLine!(char, char)))'
Still an error.
import std.array
Thx, finaly, this is so much harder to understand than c++
iostream
Re: reading file byLine
ep18.d(10): Error: no property 'split' for type 'char[]' /usr/include/dmd/phobos/std/algorithm.d(427): instantiated from here: MapResult!(__lambda1, ByLine!(char, char)) ep18.d(10):instantiated from here: map!(ByLine!(char, char)) and then a long list to the end of my code Error: undefined identifier a Hmm, seems I forgot to add std.string, now it works, but words seems not to be an array, at least I cannot access it like an array. words[0][0] leads to Error: no [] operator overload for type MapResult!(__lambda1, ByLine!(char, char)) So is is a map? How can I convert all the elements in it to integer and store it in a real array?
Re: reading file byLine
On Thursday, 3 September 2015 at 23:25:52 UTC, Jordan Wilson
wrote:
And also:
import std.algorithm
Sorry, I should have taken the time to answer properly and
fully.
import std.file, std.stdio, std.string, std.conv, std.algorithm;
void main(){
auto file = File("text.txt");
auto numbers = file.byLine()
.map!(a => a.split)
.map!(a => map!(a => to!int(a))(a))
.array();
writeln(numbers);
}
Error: no property 'array' for type 'MapResult!(__lambda2,
MapResult!(__lambda1, ByLine!(char, char)))'
Still an error.
Re: How to test if a double has no fraction part
Interesting, in contrary to C++ it saves the integral part in the
dummy variable. Doing this I noticed if I try to write a double
variable in the console it gives me only the integral part. I
only did it with writeln so far. How can I print out a double
variable with a precision of 2 for instance? I tried it with
writefln("%d", d)
It compiles but crashes.
Re: reading file byLine
Hope this helps. Yes, it does. I have a question about arrays. I can sort an array A by sort(A); How can I get just the maximum element? Do I need to give a range for it?
Re: reading file byLine
Thx guys, this helped alot. The next thing I want to do is read
the file line by line and split the stream into words. I found
this example of code that seems to do sort of something like it.
How can I modyfy it so I can store the words in an array of
strings? Is a => a.length the iterator range?
import std.algorithm, std.stdio, std.string;
// Count words in a file using ranges.
void main()
{
auto file = File("file.txt"); // Open for reading
const wordCount = file.byLine()// Read lines
.map!split // Split into words
.map!(a => a.length) // Count words per
line
.sum(); // Total word count
writeln(wordCount);
}
Re: reading file byLine
On Wednesday, 2 September 2015 at 13:12:39 UTC, cym13 wrote:
On Wednesday, 2 September 2015 at 13:01:31 UTC, Namal wrote:
Hello,
I want to read a file line by line and store each line in a
string. I found this example with byLine and ranges. First of
all, do I need the range lib at all to do this and if so what
is the range of the end of the file?
You don't need the range lib at all, std.range provides
advanced functions to work with ranges but ranges are a general
concept. You need std.stdio though as this is doing file
operations.
A way to do it is:
void main() {
auto f = File("myfile");
string buffer;
foreach (line ; f.byLine) {
buffer ~= line;
}
f.close();
writeln(buffer);
}
Note that by default byLine doesn't keep the line terminator.
See http://dlang.org/phobos/std_stdio.html#.File.byLine for
more informations.
Thx, cym. I have a question about a D strings though. In c++ I
would just reuse the string buffer with the "=" how can I clear
the string after i store a line in the buffer and do something
with it. I also tried to append a line to an array of strings but
it failed because the line is a char?
reading file byLine
Hello, I want to read a file line by line and store each line in a string. I found this example with byLine and ranges. First of all, do I need the range lib at all to do this and if so what is the range of the end of the file?
Re: array function
On Monday, 31 August 2015 at 11:27:20 UTC, Rikki Cattermole wrote:
You cannot define static arrays using runtime information.
You must use dynamic arrays.
int[] foo(int N) {
int[] v;
v.length = N;
// do something with it
int[] 2;
return s;
}
Of course you can pass it in via a template argument. But this
of course does not work at runtime like you are wanting.
Hmm, this has never been a problem for me in C++
#include
std::vector foo(int N){
std::vector V(N);
int some_array[N];
std::vector other_V;
return other_V;
}
int main(){
std::vector V = foo(12);
}
compiles
array function
Hello,
can someone explain to me please what I am doing wrong by passing
an integer to this function and then just creating a static
array? The error I get is:
Error: variable N cannot be read at compile time
int[] foo(int N){
int[N] v;
//do something with it
int[] s;
return s;
}
void main(){
int N = 12;
int[] A;
A=prim_numbers(N);
}
Re: array function
Hey guys, since I am learning D arrays here, can you tell me the best way to remove an element at the end of an array or at some index i?
Re: array function
On Monday, 31 August 2015 at 12:00:26 UTC, bearophile wrote:
Namal:
std::vector foo(int N){
std::vector V(N);
int some_array[N];
VLAs are not present in D.
Bye,
bearophile
Yah, I guess I have been damaged with them when I started to
learn programming in C++ >(
Setting um makefile for dmd
Hello, i get myself a nice makefile from here: https://gist.github.com/darkstalker/2221824 How can I modify it so that I can use the run option of dmd? I tried to add another compiler flag variable which would be only used with run but then it messed with -of$@ option and said it couldn't read it. Thanks
