For simple C cmd programs: how to add "program executed in 12,345 seconds"?

There's a function in time.h header clock_t clock();

It returns a number of hardware timer clocks expired since launch of the program To get real time you can divide that number by constant CLOCKS_PER_SEC which is also defined in time.h

The full method would be:

void print_time_since_launch() { printf ("Execution time %f", clock() / CLOCKS_PER_SEC); } 

You can use it in your program like this:

static clock_t s_start_time; void start_clock() { s_start_time = clock(); } void display_execution_time() { clock_t now = clock(); double secs = (now - s_start_time) / (double)CLOCKS_PER_SEC; printf("Execution time: %g secs\n", secs); } int main() { start_clock(); /* do your thing */ display_execution_time(); } 

The reason that it does not work on some PCs is ... See my answer on

How precise is the internal clock of a modern PC?

#include <mmsystem.h> int main() { DWORD start = timeGetTime(); //Do work DWORD end = timeGetTime(); printf("execution time: %.3f s\n", float(end - start) / 1000.0f); }