Command line arguments

To pass command line arguments to a program, define main() with two arguments. The argc argument is the number of command line arguments including the program name while argv is the list of arguments passed to the program.

// commandline.cpp

#include <iostream>

int main(int argc, char const *argv[])
    /* code */
    std::cout << "argc is " << argc << std::endl;
    std::cout << "argv 0 is " << argv[0] << std::endl;
    std::cout << "argv 1 is " << argv[1] << std::endl;

    return 0;

Compile and run the program and pass an argument to it.

clang++ commandline.cpp -o commandline
./commandline hellothere

The printed output for the above example is shown below.

argc is 2
argv 0 is ./commandline
argv 1 is hellothere

Gavin Wiggins © 2022