How To find Execution Time In C/C++

 There is two way to find execution time in C/C++.

We give differed inputs to get differed executions time.

1. 512*512

2.1024*1024

3.2048*2048

1st way Copy The code and Run It give input in array: 

#include <stdio.h> 

#include <time.h> 

int m={1},n={1};

int array[2048][2048];

// A function that terminates when enter key is pressed 

void fun() 

{ 

printf("fun() starts \n"); 

printf("Press enter to stop fun \n"); 

for(int kk=0;kk<1000;kk++)

{

int sum={0};

for(int i=0;i<m;i++)

{

for(int j=0;j<n;j++)

sum+=array[2048][2048];

}

}

printf("fun() ends \n"); 

}

 

// The main program calls fun() and measures time taken by fun() 

int main() 

{ 

// Calculate the time taken by fun() 

clock_t t; 

t = clock(); 

fun(); 

t = clock() - t; 

double time_taken = ((double)t)/CLOCKS_PER_SEC; // in seconds 

printf("fun() took %f seconds to execute \n", time_taken); 

return 0; 

}

2nd way Copy The code and Run It give input in array

#include <iostream> 

#include <time.h> 

using namespace std;

// A function that terminates when enter key is pressed 

void fun() 

{ 

cout<<"fun() starts \n"; 

 

int A[512][512],N,M,sum,i,j,kk;

for(kk=0;kk<1000;kk++)

{ sum = 0;

for (i = 0; i < M; i++)

for (j = 0; j < N; j++)

sum += A[j][i];

}

cout<<"fun() ends \n"; 

} 

int main() 

{ 

// Calculate the time taken by fun() 

clock_t t; 

t = clock(); 

fun(); 

t = clock() - t; 

double time_taken = ((double)t)/CLOCKS_PER_SEC; // in seconds 

cout<<" took %f seconds to execute  "<<time_taken; 

}