C_(visual)_Debug Error_ Run-Time Check Failure #2 -S - c

Question

I want to reverse numbers of array,
but I can't understand why it didn't run.
Thanks for explaining what does Debug Error_ Run-Time Check Failure #2 -S mean..
Thanks,
#include <stdio.h>
int main()
{
int arr[] = { 1,2,3,4,5 };
int size, i, j;
int temp = 0;
size = sizeof(arr) / sizeof(arr[0]); //use this for changing size
printf("first_array :");
for (i = 0; i < size; i++)
{
printf("%d", arr[i]);
}
printf("\n");
for (i = 0; i <= (size / 2); i++)
{
j = size - i;
temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
printf("Riv_array :");
for (i = 0; i < size; i++)
{
printf("%d", arr[i]);
}
return 0;
}

Answer 1

Array index starts from 0 in C and your array has 5 elements so arr[4] is the last element but your code:
j = size - i;
arr[j];
when i=0 access to arr[5], this is your code error: Array index out of bound.
you should use j = size - i-1; to point to the last element of array, not j = size - i;
see this working sample (your sample code with some edit):
#include <stdio.h>
int main()
{
int arr[] = { 1, 2, 3, 4, 5 };
int size, i, j;
int temp = 0;
size = sizeof(arr) / sizeof(arr[0]); //use this for changing size
printf("first_array :");
for (i = 0; i < size; i++)
{
printf("%d ", arr[i]);
}
printf("\n");
for (i = 0; i <= (size / 2); i++)
{
j = size - i - 1;
temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
printf("Riv_array :");
for (i = 0; i < size; i++)
{
printf("%d ", arr[i]);
}
return 0;
}
another way to reverse array using pointers:
#include <stdio.h>
void reverse(int* p, int count){
int temp;
int* q = p + count - 1; // point to the end
count /= 2;
while (count--) {
temp = *p;
*p++ = *q;
*q-- = temp;
}
}
void print_array(int *p, int count){
while (count--) printf("%d ", *p++);
printf("\n");
}
int main()
{
int arr[] = { 1, 2, 3, 4, 5 };
int count = ((&arr)[1] - arr);
print_array(arr, count);
reverse(arr, count);
print_array(arr, count);
return 0;
}
output:
1 2 3 4 5
5 4 3 2 1