The clock gettime function gets the current time of the clock specified by clock id and puts it into the buffer pointed to by tp.
Measure wall clock time in c.
Calculating the elapsed wall clock time of a program is helpful to determine how much time it actually takes for a program to complete.
The gettimeofday function returns the wall clock time elapsed since the epoch and store it in the timevalstructure expressed as seconds and microseconds.
Int clock gettime clockid t clock id struct timespec tp.
Note that this function does not strictly conform to iso c which specifies net cpu time as the return value.
For parallel programming the important thing to measure is the elapsed wallclock time.
To obtain cpu times use the win32 getprocesstimes function.
Using clock gettime function in c c.
For that you will have to use chronometers.
Prototype syntax.
The clock function tells how much wall clock time has passed since the crt initialization during process start.
Do the work.
As it turns out c has many functions available to get the current time.
Include sys time h int gettimeofday struct timeval restrict tp void restrict tzp.
Wtime a c function which returns a reading of the wall clock time.
In all multivalue basic languages you can use the time function to return the number of seconds from midnight.
It is defined in sys time h header file and takes two arguments the first arugment is reference to the timevalstructure and the second argument is a null pointer.
The easy method is to take the time the program ends and then subtract the time the program starts.
End clock.
This can be found by subtracting an initial reading of the wallclock time from a final one.
Cpu time used double end start clocks per sec.
Std clock time may advance faster or slower than the wall clock depending on the execution resources given to the program by the operating system.
The openmp system provides a function used as follows.
Fortunately all mpi implementations provide you with such a clock.
The system s notion of the current greenwich time and the current time zone.
For example if the cpu is shared by other processes std clock time may advance slower than wall clock.
Tp parameter points to a structure containing atleast the following members.
Following is a sample c program where we measure time taken by fun.