Check out example codes for "subarray sum in c++". It will help you in understanding the concepts better.

Code Example 1

/* A simple program to print subarray  
with sum as given sum */
#include <bits/stdc++.h> 
using namespace std; 
  
/* Returns true if the there is a subarray  
of arr[] with sum equal to 'sum' otherwise  
returns false. Also, prints the result */
int subArraySum(int arr[], int n, int sum) 
{ 
    int curr_sum, i, j; 
  
    // Pick a starting point 
    for (i = 0; i < n; i++) { 
        curr_sum = arr[i]; 
  
        // try all subarrays starting with 'i' 
        for (j = i + 1; j <= n; j++) { 
            if (curr_sum == sum) { 
                cout << "Sum found between indexes "
                     << i << " and " << j - 1; 
                return 1; 
            } 
            if (curr_sum > sum || j == n) 
                break; 
            curr_sum = curr_sum + arr[j]; 
        } 
    } 
  
    cout << "No subarray found"; 
    return 0; 
} 
  
// Driver Code 
int main() 
{ 
    int arr[] = { 15, 2, 4, 8, 9, 5, 10, 23 }; 
    int n = sizeof(arr) / sizeof(arr[0]); 
    int sum = 23; 
    subArraySum(arr, n, sum); 
    return 0; 
} 
  
// This code is contributed 
// by rathbhupendra

Code Example 2

/* An efficient program to print  
subarray with sum as given sum */
#include <iostream> 
using namespace std; 
  
/* Returns true if the there is a subarray of  
arr[] with a sum equal to 'sum' otherwise  
returns false. Also, prints the result */
int subArraySum(int arr[], int n, int sum) 
{ 
    /* Initialize curr_sum as value of  
    first element and starting point as 0 */
    int curr_sum = arr[0], start = 0, i; 
  
    /* Add elements one by one to curr_sum and  
    if the curr_sum exceeds the sum, 
    then remove starting element */
    for (i = 1; i <= n; i++) { 
        // If curr_sum exceeds the sum, 
        // then remove the starting elements 
        while (curr_sum > sum && start < i - 1) { 
            curr_sum = curr_sum - arr[start]; 
            start++; 
        } 
  
        // If curr_sum becomes equal to sum, 
        // then return true 
        if (curr_sum == sum) { 
            cout << "Sum found between indexes "
                 << start << " and " << i - 1; 
            return 1; 
        } 
  
        // Add this element to curr_sum 
        if (i < n) 
            curr_sum = curr_sum + arr[i]; 
    } 
  
    // If we reach here, then no subarray 
    cout << "No subarray found"; 
    return 0; 
} 
  
// Driver Code 
int main() 
{ 
    int arr[] = { 15, 2, 4, 8, 9, 5, 10, 23 }; 
    int n = sizeof(arr) / sizeof(arr[0]); 
    int sum = 23; 
    subArraySum(arr, n, sum); 
    return 0; 
} 
  
// This code is contributed by SHUBHAMSINGH10

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