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Unexpected results when using `printf` with dynamic memory in C - values printed are incorrect

👀 Views: 92 đŸ’Ŧ Answers: 1 📅 Created: 2025-06-05
c dynamic-memory printf C

I'm stuck trying to I'm testing a new approach and I've spent hours debugging this and I'm working with an scenario where the values printed using `printf` are not what I expect when these values are stored in a dynamically allocated array. I'm using GCC version 11.2 on Ubuntu 20.04. Here's the relevant code snippet: ```c #include <stdio.h> #include <stdlib.h> void initializeArray(int **arr, int size) { *arr = (int *)malloc(size * sizeof(int)); if (*arr == NULL) { perror("Failed to allocate memory"); exit(EXIT_FAILURE); } for (int i = 0; i < size; i++) { (*arr)[i] = i * 10; // Initialize with multiples of 10 } } int main() { int *myArray; int size = 5; initializeArray(&myArray, size); for (int i = 0; i < size; i++) { printf("Value at index %d: %d\n", i, myArray[i]); } free(myArray); return 0; } ``` When I run this code, I expect to see: ``` Value at index 0: 0 Value at index 1: 10 Value at index 2: 20 Value at index 3: 30 Value at index 4: 40 ``` but instead, I see garbage values printed for the initialized array. I've checked that the allocation is successful and the initialization loop seems fine. I even added checks to ensure that memory allocation is done correctly and the values should be set. I've also tried using `valgrind` to check for memory leaks or invalid reads, but it doesn't show any issues. Is there something I'm overlooking in how I'm passing the pointer around or in the way the memory is allocated? Any insights would be greatly appreciated. Any ideas how to fix this? Hoping someone can shed some light on this. I recently upgraded to C latest.