What does (int argc, char *argv[]) do?

The C/C program writes a command line argument.

argc indicates the number of strings pointed to by argv.

It is customary to write argc(argument count) and argv(argument vector) (intnum_args, char**arg_string) It is okay to use another identifier.

For example,

#include <iostream>

int main(int argc, char** argv) {
    std::cout << "Have " << argc << " arguments:" << std::endl;
    For (inti = 0; i < argc; ++i) { // number of factors (argc) output
        std::cout << argv[i] << std::endl;
    }
}

If you run the code together with ./testa1 b2 c3

Have 4 arguments:
./test
a1
b2
c3

will be printed.