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Calculation in parent and child process using fork()

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Write a program to find sum of even numbers in parent process and sum of odd numbers in child process.


Input : 1, 2, 3, 4, 5 

Output :
Parent process 
Sum of even no. is 6
Child process 
Sum of odd no. is 9 

Explanation: Here, we had used fork() function to create two processes one child and one parent process. 

  • For child process fork() returns 0 so we can calculate sum of all odd numbers in child process. 
  • fork() returns value greater than 0 for parent process so we can calculate sum 
  • for all even numbers there by just simply checking the value returned by fork(). 


// C++ program to demonstrate calculation in parent and
// child processes using fork()
#include <iostream>
#include <unistd.h>
using namespace std;
// Driver code
int main()
    int a[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
    int sumOdd = 0, sumEven = 0, n, i;
    n = fork();
    // Checking if n is not 0
    if (n > 0) {
        for (i = 0; i < 10; i++) {
            if (a[i] % 2 == 0)
                sumEven = sumEven + a[i];
        cout << "Parent process \n";
        cout << "Sum of even no. is " << sumEven << endl;
    // If n is 0 i.e. we are in child process
    else {
        for (i = 0; i < 10; i++) {
            if (a[i] % 2 != 0)
                sumOdd = sumOdd + a[i];
        cout << "Child process \n";
        cout << "\nSum of odd no. is " << sumOdd << endl;
    return 0;


Parent process 
Sum of even no. is 30
Child process 
Sum of odd no. is 25

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Last Updated : 13 Sep, 2021
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