C program to find time taken by a program or function to execute in seconds

Write a program in C to calculate the execution time of a program in seconds.
How to find the time taken by a function or statement to execute in C.

To find the execution time of a C program, we will use clock() function of time.h header file.

clock() function returns the number of clock ticks elapsed since the program started.
To find the total execution time of a program we will call clock function twice, once at the beginning of main function and then again at the end of main function.
Now, the total execution time of a program(in units of cpu clock ticks) is the difference between these two time instances.
To get the execution time in seconds, we will need to divide the difference by CLOCKS_PER_SEC(the number of clock ticks per second).

Placement of clock() function to find execution time of C program

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

int main() {
clock_t start, end;
double execution_time;
start = clock();

/* Put your code here */

end = clock();
execution_time = ((double)(end - start))/CLOCKS_PER_SEC;

C program to find execution time of a program

#include <stdio.h>
#include <time.h>
 
int main() {
    clock_t start, end;
    /* Store start time here */
    start = clock();
    /* put the main body of your program here */
    printf("Enter any character\n");
    getchar();
    /* program logic ends here */
    end = clock();
    /* Get the time taken by program to execute in seconds */
    double duration = ((double)end - start)/CLOCKS_PER_SEC;
     
    printf("Time taken to execute in seconds : %f", duration);
    return 0;
}

Output

Enter any character
d
Time taken to execute in seconds : 2.371000

C program to find execution time of a functionn

#include <stdio.h>
#include <time.h>
 
void my_function(){
    /* Body of function */
    float f;
    for(f=0.0; f<1000000; f=f+1.0);
}
int main() {
    clock_t start, end;
    /* Store time before function call */
    start = clock();
    my_function();
    /* Store time after function call */
    end = clock();
    /* Get the time taken by program to execute in seconds */
    double duration = ((double)end - start)/CLOCKS_PER_SEC;
     
    printf("Time taken to execute in seconds : %f", duration);
    return 0;
}

Output

Time taken to execute in seconds : 0.015000

C program to find execution time of a program

C program to find execution time of a functionn

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