Why Doesn't Passing a C-Style 2D Array to a Function Expecting `int` Work in C ?

Why Passing a C-Style Multidimensional Array to a Function Taking an Array of int* Fails in C

Issue:

In C , passing a multidimensional C-style array to a function expecting an array of int* results in a compiler error.

Reason:

A multidimensional array like int4 is not directly convertible to a pointer of type int*, which is what int arr[] represents in the function declaration.

Example:

#include<stdio.h>
void print(int *arr[], int s1, int s2) {
    // ...
}

int main() {
    int a[4][4] = {{0}};
    print(a, 4, 4); // Error in C++
}

C will report an error:

cannot convert `int (*)[4]' to `int**' for argument `1' to `void print(int**, int, int)'

Solution:

In both C and C , passing a multidimensional array as int** is not valid. To achieve this effectively, the array must be converted to a pointer using the following technique:

• Initialize the array to a different value (e.g., {1}) to verify that C has not overlooked the array passing bug.
• Modify the printf statement to access elements correctly using ((arr i) j) or arri.
• Utilize the workaround presented in the Stack Overflow thread "Converting multidimensional arrays to pointers in c ".

Note:

Ignoring compiler warnings or failing to implement the proper conversion may result in undefined behavior and unpredictable results.

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