Pointers Run time error

Question

I have used the below code for a simple operation (to reverse a string). But the program is not executing. It gets a run time error (SIGSEGV) . I used a GCC compiler. Please help me in debugging the program.

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

int *create(int n) {
    int *a;
    a = (int *)malloc(n * sizeof(int));
    return a;
}

void get(int *a, int n) {
    int i;
    for (i = 0; i < n; i++) {
        scanf("%d", *(a + i));
    }
}

void reverse(int *a, int n) {
    int i;
    for (i = n - 1; i >= 0; i--) {
        printf("\n %d", *(a + i));
    }
}

int main() {
    int n, *a;
    scanf("%d", &n);
    a = create(n);
    get(a, n);
    reverse(a, n);
    return 0;
}

Answer 1

scanf("%d",*(a+i)); invokes undefined behavior because you passed int where int* is expected.

You must pass pointer to tell scanf() where to store the data read, so stop dereferencing and try using scanf("%d",(a+i)); instead.

More notes are:

• You should check if readings are successful.
• They say you shouldn't cast the result of malloc() in C.