COMP20005 how to time a program

Some students have asked me how to time the running of a program. Essentially, the problem is how do we know the amount of time that a program takes to run. In C, you can use functions from the header file time.h to time your program. The program below shows how to do a simple timing of a program.

#include <stdio.h> 
#include <time.h>

int main(int argc, char **argv) { 
  char name; 
  double howlong; 
  time_t start, end; 

  start = time(NULL); 
  printf("Enter your name: "); 
  scanf("%s", &name); 
  end = time(NULL); 
  howlong = difftime(end, start); 
  printf("You took %.3lf seconds, %s\n", howlong, &name); 

  return 0; 
}

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