Segmentation fault when using malloc and realloc with arrays

Question

I'm fairly new to c and I'm trying to understand and grasp malloc. My program takes an integer x input, then loops until x is met while also taking other integer inputs. I then do various calculations. However I'm getting a segmentation fault and I don't understand why.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int main(void)
{

    calculations();
}

void calculations()
{

    int i;
    int x;
    int total = 0;
    double squareRoot;
    double overall;

    scanf("%d", &x);

    int* array = malloc(x * sizeof(int));

    if (!array) {
        printf("There isn't enough memory \n");
        return;
    }

    int c = 0;

    while (c < x) {

        scanf("%d", &array[i]);

        total = array[i] * array[i];
        c++;
    }

    squareRoot = sqrt(total);
    array = realloc(array, x * sizeof(int));

    int b = 0;

    while (b < x) {

        overall = array[i] / squareRoot;
        printf("%.3f ", overall);

        b++;
    }
}

Answer 1

The problem is with

 scanf("%d", &array[i])

where, the value of i is indeterminate.

To elaborate, i is an uninitialized local variable and unless initialized explicitly, the contents remain indeterminate. Attempt to use that value, in this scenario, would lead to invokes undefined behavior .

Even if you initialize i , you never operated on i , so all the changes will be overwritten on a fixed index. You got to take care of this case, too.

Solution: Looking at the code, it appears, you may want to use

scanf("%d", &array[c]);

instead.