Conflicting Types Error when Passing 2D Array to Function in C

Question

I am trying to pass a 2D array to a function that I have defined in my program, but for some reason, I am continuously getting an error about conflicting types for the function call and definition. I am not entirely sure what could be causing the issue since I have not only included the right header, but also used the proper parameter type in the function indicating that it is a 2D array. Below is the code that I am writing.

#include <stdio.h>
#include <stdbool.h>

int main()
{
    char array[6][6] = {
        {'.', '.', '.', '.', '.', '.'},
        {'.', '.', '.','.', '.', '.'},
        {'.', '.', '.', '.', '.', '.'},
        {'.', '.', '.', '.', '.', '.'},
        {'.', '.', '.', '.', '.', '.'},
        {'.', '.', '.', '.', '.', '.'}
    };
    
    bool success = testFunction(array, 0, 1);

    return 0;
}


bool testFunction(char array[][6], int i, int j){
    return true;
}

And this is the error that I receive after running the program:

main.c:21:6: error: conflicting types for ‘testFunction’
   21 | bool testFunction(char array[][6], int i, int j){

It's really confusing me and after looking at previous posts on StackOverflow I cannot seem to find what could be causing this issue. I know this problem could possibly be solved if I converted the array into a pointer, but is it not possible to pass 2D arrays to function? If anyone could help me find a way to solve this, I'd truly appreciate it. Thank you.

Turn on all compiler warnings...

Andrew Henle
– Andrew Henle

2021-10-23 23:39:29 +00:00
Commented Oct 23, 2021 at 23:39 — Andrew Henle
– Andrew Henle, Commented Oct 23, 2021 at 23:39

0___________ · Accepted Answer · 2021-10-23 23:41:40Z

3

You need to define it before the main function or put there the function prototype

bool testFunction(char array[][6], int i, int j);

answered Oct 23, 2021 at 23:41

0___________

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2 Comments

africanxmamba Over a year ago

Thank you, that seemed to fix the issue, but why does defining it before main() fix the issue? Why does the order of where functions are defined impact the output?

isrnick Over a year ago

@StriveForGreatness Yes, you must always declare something before using it. This is logical, after all the code can't use something it doesn't know exists yet.

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