Owen Densmore wrote:
> So the *extremely* common bug
> of using = rather than == causes entirely unexpected consequences ..
> launching a missile.
>
I expect to see both in many circumstances.
For example, when opening a file to read that is absent or to write, and
write permission is forbidden.
if ((fp = fopen (filename, "r")) == NULL)
abort ();
I haven't really created many bugs because of "=" vs. "==". GCC even
gives a warning...
$ cat t.c
#include <stdio.h>
#include <stdlib.h>
static void
launch_missle ()
{
printf ("Missle launched\n");
}
int
main (int argc, const char **argv)
{
int red_button_pressed = 0;
if (argc > 1)
red_button_pressed = atoi (argv[1]);
if (red_button_pressed = 1)
launch_missle ();
return 0;
}
$ gcc -Wall t.c
t.c: In function ‘main’:
t.c:18: warning: suggest parentheses around assignment used as truth value
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