segmentation fault checking user arguments c

Question

I am trying to validate user input from the command line with argc and argv but am running into a segmentation fault and am not sure why.

I want to validate the user has

Answer 1

Your main should be

int main(int argc, char*argv[])

And do the check before using on atoi on argv[1]

Also all paths should return a value. Bung return 0; at the end