clock_t

< c‎ | chrono
Defined in header <time.h>
typedef /* unspecified */ clock_t;

Arithmetic (until C11)Real (since C11) type capable of representing the processor time used by a process. It has implementation-defined range and precision.

Example

#include <stdio.h>
#include <time.h>
#include <math.h>
 
volatile double sink;
int main (void)
{
  clock_t start = clock();
 
  for(size_t i=0; i<3141592; ++i)
      sink+=sin(i);
 
  clock_t end = clock();
  double cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;
 
  printf("for loop took %f seconds to execute \n", cpu_time_used);
}

Possible output:

for loop took 0.271828 seconds to execute

References

  • C17 standard (ISO/IEC 9899:2018):
  • 7.27.1/3 Components of time (p: 284)
  • C11 standard (ISO/IEC 9899:2011):
  • 7.27.1/3 Components of time (p: 388)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.23.1/3 Components of time (p: 338)
  • C89/C90 standard (ISO/IEC 9899:1990):
  • 4.12.1 Components of time

See also

 returns raw processor clock time since the program is started
(function)
number of processor clock ticks per second
(macro constant)