Learn C++ Online

This lesson contains approximately 10 minutes of video content.

Command line arguments

Passing arguments to main

In the above video, I compile in an older version of our environment with clang++-10. In your updated environment, you should use clang++.

QQ1

This question is ungraded.

According to the lesson videos, if you are interested in using an argument stored in argv in your program, how should you interact with its value?

Assign argv[i] to argc; use argc throughout your program in place of argv[i].

Initialize an std::string with argv[i], where i is the argument you're interested in using. Thereafter, use the std::string in place of argv[i].

Use argv[argc] throughout your program.

Use argv[i], where i is the argument you're interested in using, throughout your program.

Practice question: try as many times as you like

QQ2

This question is ungraded.

Assume you have compiled a C++ program with a main(int argc, char* argv[]) function down to the executable a.out. If you execute ./a.out "Howdy, World" from the command line, what will be stored in argv[0]?

./a.out

Howdy

Howdy, World

World

Practice question: try as many times as you like

QQ3

This question is ungraded.

Assume you have compiled a C++ program with a main(int argc, char* argv[]) function down to the executable a.out. If you execute ./a.out from the command line, what will be stored in argc?

(nothing)

./a.out

0

1

Practice question: try as many times as you like

QQ4

This question is ungraded.

Given the following program code:

#include <iostream>

int main(int argc, char* argv[]) {
  if (argc != 1) {
    std::cout << "Usage: " << argv[0] << std::endl;
    return 1;
  }
  std::cout << "Whoop!" << std::endl;
  return 0;
}

Assume you have compiled that program down to the executable a.out. If you execute ./a.out Howdy, World! from the command line, what will be the output of the program?

Usage: ./a.out

Usage: Howdy, World!

Usage: argv[0]

Whoop!

Practice question: try as many times as you like