next up previous contents index
Next: File Handles Up: Input/Output Previous: Standard Input/Output/Error   Contents   Index

Command line arguments

Another method to get user inout is through the use of command-line arguments when running a program:
  my_program 34 66 dallas
where the arguments 34, 66, and dallas are captured and subsequently used in your program. How this can be done is illustrated in the following program:
#include <stdio.h>

int main(int argc, char *argv[]) {
  int input;

  if (argc != 2) {
    printf("Usage: %s number\n", argv[0]);
  input = atoi(argv[1]);
  printf("You entered an integer %d.\n", input);
  return 0;
Here, It is important to realize that the arguments will be captured as strings (arrays of characters); the functions atoi and atof can be used to convert a string to, respectively, an integer and a double.