What is a command-line argument?

Command-line arguments aresimple parameters that are given on the system's command line, and the values of these arguments are passed on to your program during program execution. When a program starts execution without user interaction, command-line arguments are used to pass values or files to it. read less

You might be familiar with the following simple way to define the main function: int main() {/* blah blah */}but, the more general way to define main is as followsint main(int argc, char* argv[]) {/* blah blah */}Suppose you compile this file into say a.out, and then if you execute the program from the terminal (command prompt) as follows> ./a.out Hello World the words Hello, and World are called as command-line arguments, and a.out is the executable (or program). When executed as mentiond above, the values of argc and argv that the main function recieves would be as follows: argc gets a value of 3 (the length of the argv array) argv[0] points to a string with contents "./a.out" argv[1] points to a string with contents "Hello" and argv[2] points to a string with contents "World" Within the main function, you can program different behaviours depending on these variables. Learn by doing: Compile the following and execute it with different command-line arguments to see it in action: #include <stdio.h> int main(int argc, char* argv[]) { int i = 0; for(i = 0; i < argc; i++) printf("%s\n", argv[i]); return 0; } read less