Re: Using argv[1] in C program

On Sat, 2005-01-15 at 10:19, David Koopman wrote:
> I have a simple C question, hoping someone can help.
>
> I was doing this on one machine:
>
> let i=0; while [ $i -lt 1 ]; do
> # some action
> usleep 200000
> done
>
> I then moved to a different machine and "usleep" was not a binary on the
> new machine. So, I created a quick c file:
>
> shell> vi usleep200000.c
>
> int main() {
> usleep(200000);
> }
>
>
> shell> make usleep200000
>
> Now I can accomplish this same thing:
>
> let i=0; while [ $i -lt 1 ]; do
> # some action
> ./usleep200000
> done
>
>
> So, now for my question....
>
> How do I change my C program to take the milliseconds to sleep from the
> command line? I think it's something like this:
>
> int main(argc, argv) {
> usleep(argv[1]);
> }
>
> But that doesn't work, it says:
>

> cc     usleep.c   -o usleep
> usleep.c: In function `main':
> usleep.c:2: error: subscripted value is neither array nor pointer
> make: *** [usleep] Error 1

>
>
> help?

I think what you're looking for is atoi(char*). (see `man atoi` for
other options).

The parameter to usleep needs to be an unsigned long.

Bart

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