Segmentation fault, first time with 2D arrays

Question

I am working with 2D arrays for the first time for a sudoku checker program; below is my code.

My program compiles without error, but when I run it, it gives me a segmentation fault.

It has been a while since I last coded, so I am unsure what I'm missing. I've also never had to deal with this error before.

My Code:

#include <stdio.h>
#include <stdlib.h>
int sudokuCheck();
int arrayMake();
#define SIZE 9

int main(){
    int sudokAmount;

    printf("Please Enter the amount of solutions to solve:\n");
    scanf("%d",&sudokAmount);
    arrayMake();
    //sudokuCheck(sudokAmount);
    return 0;
}

int arrayMake(){
    int j;
    int i;
    int** sudoArr;

    sudoArr = malloc(sizeof(int*) * SIZE * SIZE);
    printf("Please Enter Sudoku Solutions(By rows)\n");
    for(i = 0; i < SIZE; i++){
        for(j=0; j < SIZE; j++){
            scanf("%d\n", &sudoArr[i][j]);
        }
    }
    for(i = 0; i < SIZE; i++){
        for(j=0; j < SIZE; j++){
            printf("%d \n", sudoArr[i][j]);
        }
    }

    return 0;
}

Do you have access to a debugger (maybe gdb, lldb, etc..)? Try running a backtrace and posting what pops up here so we have more information. — Yashwanth, Sep 02 '15 at 21:42
change to `int (*sudoArr)[SIZE]; sudoArr = malloc(sizeof(*sudoArr) * SIZE );` or `int (*sudoArr)[SIZE] = malloc(sizeof(int) * SIZE * SIZE);` — BLUEPIXY, Sep 02 '15 at 21:45
For this code it's silly to do dynamic allocation at all. Since the array dimensions are statically known, and it is used only inside the function where it is declared, `int sudoArr[SIZE][SIZE];` (and no `malloc()`) would be better. If it needed to be shared among functions then it could be declared that way as a global, or it could be declared that way in `main()` and passed as an argument to the other functions. — John Bollinger, Sep 02 '15 at 22:14
@JohnBollinger I see, I was just trying to practice dyn arrays but I guess I'll try a fixed array. — Jude, Sep 02 '15 at 22:16

Denis Babarykin · Accepted Answer · 2015-09-02T22:31:22.800

1

First of all, you allocate memory for the matrix wrong way. Correct will be:

int** sudoArr = (int**)malloc(SIZE * sizeof(int*));

for (int index=0; index < SIZE; ++index)
{
    sudoArr[index] = (int*)malloc(SIZE * sizeof(int));
}

Link to online compiler with correct version of your code: correct sources

edited Sep 02 '15 at 22:31

answered Sep 02 '15 at 21:50

Denis Babarykin

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Segmentation fault, first time with 2D arrays

1 Answers1