On Saturday, 9 March 2019 at 18:11:09 UTC, Jacob Shtokolov wrote:w
One of the task was to take a string from STDIN and detect its
type.
The way I'd do this is a very simple loop:
enum Type { String, Float, Int }
if(str.length && str[0] == '-') {
str = str[1 .. $];
}
Type type = str.length ? Type.Int : Type.String;
foreach(ch; str) {
if(ch == '.' && type = Type.Int)
type = Type.Float;
else if(ch < '0' || ch > '9') {
type = Type.String;
break;
}
}
And if you need to support other details, add them on top of
that. For example, exponents on floats may be a second clause
like how I put negative ahead.
You may also choose to use a regular expression though I think
that is overkill for this.
if (data.isNumeric) {
There are several caveats on that isNumeric function: it sees if
something looks like a D numeric literal, which might not be what
you want. For example, isNumeric("1UL") passes because the U and
L suffixes are allowed in D literals...
But I think that's ugly. The thing is that in PHP, for example,
I would do that like this:
```
if (is_integer($data)) {
Simiarly, this also will not od what you want. is_integer("1")
will return false. "1" is of type string. Those functions check
the dynamic type tag, not the contents of a string.
(actually, you arguably can just always return "string" cuz stdin
is basically just a string or a binary stream anyway :P )
PHP's is_numeric returns true for both integer and floating point
things, similarly to D's...
