👀 Views: 467 💬 Answers: 1 📅 Created: 2025-07-22

c function-pointers callbacks debugging C

I'm maintaining legacy code that I'm trying to implement a callback mechanism in C using function pointers, but I'm getting unexpected output when I call my callback function. I'm using GCC version 11.1 on Ubuntu 20.04. The idea is to pass a function as a callback to another function that processes an array of integers. Here’s the relevant code: ```c #include <stdio.h> void processArray(int *arr, int size, void (*callback)(int)) { for (int i = 0; i < size; i++) { callback(arr[i]); } } void printValue(int value) { printf("Value: %d\n", value); } int main() { int numbers[] = {1, 2, 3, 4, 5}; processArray(numbers, 5, printValue); return 0; } ``` When I run this code, I expect to see each value printed out as `Value: 1`, `Value: 2`, and so on. However, instead of getting the expected output, I see the following: ``` Value: 4 Value: 5 Value: 6 Value: 7 Value: 8 ``` The output seems to start from 4 and goes up, but I need to figure out why. I've checked that the array is correctly defined and passed to the `processArray` function. I also confirmed that the callback function `printValue` is properly set up. I suspect it might be an scenario with how I’m using the function pointer or maybe the way the for loop is iterating. Any insights on what could be causing this unexpected behavior or how I can debug this effectively? I'm developing on CentOS with C. Am I missing something obvious?