Debug check sum parity

Debug the given C++ code.

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Prompt Freeform

Debug the code:

#include <iostream>
#include <exception>

using namespace std;

void check_sum_parity(int* arr, int arrayLength) {
    for (int i = 0; i < arrayLength; i++) {
        sum_of_numbers += arr[i];
    }
    if (sum_of_numbers % 2 == 0) {
        cout << "Sum is odd." << endl;
    }
    else {
        cout << "Sum is even." << endl;
    }
}

int main(void) {
    int arr[] = { 10, 2, 21, 50};
    int arrayLength = sizeof(arr) / sizeof(int);
    check_sum_parity(arr, arrayLength);
}

Response

Of course! Let's debug the code.

There are two main issues in the check_sum_parity function:

  1. Compilation Error: The variable sum_of_numbers is used in the for loop without being declared or initialized first. You must declare it as an integer and initialize it to 0 before you start adding to it.
  2. Logical Error: The if/else block has its output messages swapped. When sum_of_numbers % 2 == 0 is true, it means the sum is even, but the code prints "Sum is odd." The same mistake is in the else block.

Corrected Code

Here is the corrected version of the code with comments highlighting the fixes.

#include <iostream>
// #include <exception> // This include is not used, so it can be removed.

using namespace std;

void check_sum_parity(int* arr, int arrayLength) {
    // FIX 1: Declare and initialize the sum variable before using it.
    int sum_of_numbers = 0;

    for (int i = 0; i < arrayLength; i++) {
        sum_of_numbers += arr[i];
    }

    // FIX 2: Correct the logic in the if/else block.
    if (sum_of_numbers % 2 == 0) {
        // If the remainder when divided by 2 is 0, the number is even.
        cout << "Sum is even." << endl;
    }
    else {
        // Otherwise, the number is odd.
        cout << "Sum is odd." << endl;
    }
}

int main(void) {
    int arr[] = { 10, 2, 21, 50};
    int arrayLength = sizeof(arr) / sizeof(int);
    check_sum_parity(arr, arrayLength);
    return 0; // Good practice to return 0 from main
}

Summary of Changes:

  1. Added int sum_of_numbers = 0;: This line was added before the for loop to properly initialize the variable that will hold the sum.
  2. Swapped cout Statements: The messages inside the if and else blocks were swapped to correctly report whether the sum is even or odd.

Output of the Corrected Code

For the given array { 10, 2, 21, 50 }, the sum is 10 + 2 + 21 + 50 = 83. Since 83 is an odd number, the corrected program will now correctly print:

Sum is odd.
Model: gemini-2.5-pro
Temperature: 0.2
Max output tokens: 8192
TopK: 40.0
TopP: 0.95