What does int argc, char *argv[] mean?

Question

In many C++ IDE\'s and compilers, when it generates the main function for you, it looks like this:

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

When I

Answer 1

Suppose you run your program thus (using sh syntax):

myprog arg1 arg2 'arg 3'

If you declared your main as int main(int argc, char *argv[]), then (in most environments), your main() will be called as if like:

p = { "myprog", "arg1", "arg2", "arg 3", NULL };
exit(main(4, p));

However, if you declared your main as int main(), it will be called something like

exit(main());

and you don't get the arguments passed.

Two additional things to note:

1. These are the only two standard-mandated signatures for main. If a particular platform accepts extra arguments or a different return type, then that's an extension and should not be relied upon in a portable program.
2. *argv[] and **argv are exactly equivalent, so you can write int main(int argc, char *argv[]) as int main(int argc, char **argv).