Question

I use a function that displays a block of memory’s content pointed by a pointer.
But didn’t get the desired output, i am new to this, please correct my if i am wrong.
when I input size =3, element = 1,2,3 , I got output = 1 only.

Here’s the code:

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

void merge(int **arr1);

int main(void) {
    int size1;
    printf("Give me the size of first array\n");
    scanf("%d", &size1);

    int *arr1 = malloc(size1*sizeof(int));
    int *p1=arr1;
    printf("Give me the elements of first array\n");
    int index1;
    for(index1 = 0 ; index1<size1; index1++)
    scanf("%d", p1++);

    merge(&arr1);
    return;
}

void merge(int **arr1) {
    while(**arr1)  //**arr1 is the content of the passed array, if there 
                  // is an int in it, print that out and increment to next one
    {
        printf("%d", **arr1); // ** is the content and * is the address i think, right?
        *arr1++;
    }
}

Answer 1

Your merge() code expects the array to be terminated by zero. The calling code is not doing it, so the behavior is unspecified (I got segfault when I tried your code).

The other issue is that you should put parentheses around *arr1:

(*arr1)++;

When I run your code with this modification and enter zero for the last element, your code runs fine.