I have a hard time in understatanding how true and false works with "if statement" when I am using argv & getopt.
This is the simple code:
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
int main(int argc, char *argv[]) {
int opt;
while ((opt = getopt (argc, argv, "i:l:")) != -1)
switch (opt) {
case 'i':
printf("This is option i");
break;
case 'l':
printf("This is option l");
break;
default:
fprintf(stderr,"Usage: %s here goes usage\n",argv[0]);
}
if (argc == 1) {
printf("Without options");
}
if ((argc == 2) && (argv[1] != "-l") || (argv[1] != "-i")) {
printf("Without option -l or -i but with other argument \n");
printf("argv[1] is %s\n", argv[1]);
}
Usage:
./a.out foo
Output:
Without option -l or -i but with other argument
argv[1] is foo
It's good so far. Now let me check if it works when argv[1] is "-l":
Usage:
./a.out -l
Output:
./a.out: option requires an argument -- 'l'
Usage: ./a.out here goes usage
Without option -l or -i but with other argument
argv[1] is -l
Getopt works fine, but second information occurs even if argv[1] is -l and I set in "if" statement that (argv[1] != "-l"). Why it works like that? I have no clue.
Thanks for any answer. B.
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