Olufowobi Lawal <wolex...@...> wrote:
>
> Hi All!
> There are two possible argument to this programme (extract
> below) of the formats "192.148.14.1-192.148.14.30" and
> "192.148.14.1/21". I can successfully extract the int's
> in either scenario but my error checking seems not intuitive
> enough. I was also wondering if there is a concise way of
> extracting this int's. and performing the error checking.
Parsing input is not one of C's strong points.
> And yeah, it's an HOMEWORK that needs perfection.
I only have nitpicks...
You should show your includes. Functions like printf and sscanf
are variadic and _require_ a prototype in scope.
> int main(int argc,char *argv[]){
>
> int i,ip_add[4],ip_add2[4];
> int maskBit;
> if( argc==1){
You should also care about argc > 2, and even argc == 0.
> printf("NO INPUT!!\n");
A somewhat less than professional message. ;)
> printf("Use --help for help\t -v for version number\n");
Error messages should go to stderr. I'd also avoid \t unless
you absolutely need to use it.
> return 0;
> }
> else {
> for(i = 1; i < argc; i++)
> {
> //if any of this options is input
> if(!strcmp(argv[i], "--help") || !strcmp(argv[i],
> "/?") || !strcmp(argv[i], "-h"))
A little more whitespace would make this clearer.
> {
> help();
> return 0;
You've encountered an error, but you return a success status.
This won't suit batch scripts too well.
> }
> if(!strcmp(argv[i], "--version") || !strcmp(argv[i],
> "-v"))
> {
> version();
> return 0;
> }
> }
> }
>
>
> //to improve, incorrect input formating
> if (sscanf(argv[1], "%d.%d.%d.%d-%d.%d.%d.%d",&ip_add[0],
> &ip_add[1],&ip_add[2],&ip_add[3],&ip_add2[0],&ip_add2[1],&ip_add2
> [2],&ip_add2[3])!=8){
I suggest %3d. If the user enters a number outside the range
of int, the behaviour of sscanf is undefined.
> }
> else {
An empty if body seems awkward.
> deaggregate(ip_add,ip_add2);
You should also show prototypes for your external functions.
> return 0;
> }
>
> if( sscanf(argv[1],"%d.%d.%d.%d/%d",&ip_add[0],&ip_add
> [1],&ip_add[2],&ip_add[3],&maskBit)
> !=5 ){
> printf("Ip calculation can't be performed'\n");
> printf("Deaggregation can't be performed'\n Check Input
> for errors\n");
> return 0;
> }
> else ipcalc(ip_add,maskBit);
> return 0;
> }
Given the pattern to match, one alternative might be along the
lines of... [untested]
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
const char *arg0 = "foo";
void version(void)
{
printf("%s: version 1.0b\n", arg0);
exit(0);
}
#define f0(x) fprintf(fp, x "\n")
#define f1(x, a) fprintf(fp, x "\n", a)
void usage(FILE *fp)
{
f1("%s --version", arg0);
f1("%s --help", arg0);
f1("%s ip-ip", arg0);
f1("%s ip/mask", arg0);
f0("");
f0("Do something wonderful.");
exit(fp == stderr ? EXIT_FAILURE : 0);
}
#define FB "%4i" /* beware! %4d may be safer */
#define FIP FB "." FB "." FB "." FB
const char *sscan_ip(const char *s, int ip[4])
{
int n = 0, r;
r = sscanf(s,
FIP "%n",
&ip[0], &ip[1], &ip[2], &ip[3],
&n );
return r == 4 ? s + n : 0;
}
int main(int argc, char **argv)
{
int ip[2][4];
int mask;
char c;
const char *arg;
if (argc != 2) usage(stderr);
arg = argv[1];
if ( strcmp(arg, "-h" ) == 0
|| strcmp(arg, "--help") == 0
|| strcmp(arg, "/?" ) == 0)
usage(stdout);
if ( strcmp(arg, "-v" ) == 0
|| strcmp(arg, "--version") == 0)
version();
arg = sscan_ip(arg, ip[0]);
if (!arg) usage(stderr);
c = *arg++;
if (c == '-')
{
if (!sscan_ip(arg, ip[1])) usage(stderr);
printf("%d.%d.%d.%d-%d.%d.%d.%d\n",
ip[0][0], ip[0][1], ip[0][2], ip[0][3],
ip[1][0], ip[1][1], ip[1][2], ip[1][3]);
}
else if (c == '/')
{
if (sscanf(arg, FB, &mask) != 1) usage(stderr);
printf("%d.%d.%d.%d/%d\n",
ip[0][0], ip[0][1], ip[0][2], ip[0][3], mask);
}
else
usage(stderr);
return 0;
}
--
Peter
