Thread: Spooky segmentation fault

Hi all,

This is the code that was giving me trouble. It terminates during the first for loop for reasons that I don't understand. Debugging with gdb revealed a segmentation fault.

Code:

#include <stdio.h>

int main() {

    int *arr,size,sum=0;

    printf("Enter the size of your array: ");
    scanf("%i",&size);

    for(int i=0;i<size;i++) {
        printf("Element %i: ",i+1);
        scanf("%i",arr+i);
    }

    for(int i=0;i<size;i++) {
        sum = sum + *(arr+i);
    }

    printf("The total size is %i",sum);

    return 0;
}

I was able to fix the segmentation fault by moving the sum calculation to a separate function. But I'd like to know why the first code block is failing. Does anybody have any insight? Thanks in advance.

Fixed code:

Code:

#include <stdio.h>

int main() {

    int *arr,size;

    printf("Enter the size of your array: ");
    scanf("%i",&size);

    for(int i=0;i<size;i++) {
        printf("Element %i: ",i+1);
        scanf("%i",arr+i);
    }

    printf("The total size is %i",sum(arr,size));

    return 0;
}

int sum(int *pt,int size) {
    int sum = 0;

    for(int i=0;i<size;i++) {
        sum = sum + *(pt+i);
    }
    return sum;
}

Originally Posted by laserlight

You forgot to allocate space for the dynamic array, say by calling malloc.

That worked. Thanks for the help