C Program to find sum of perfect square elements in an array using pointers.

In C programming, finding the sum of perfect square elements in an array using pointers involves traversing the array with pointer arithmetic and checking if each element is a perfect square. A perfect square is a number that can be expressed as the product of an integer with itself (e.g., 1, 4, 9, 16, 25).

Syntax

int isPerfectSquare(int num);
int sumPerfectSquares(int *arr, int size);

Algorithm

Step 1 − Read the number of elements in the array.

Step 2 − Input the array elements.

Step 3 − Initialize sum = 0 and declare a pointer variable.

Step 4 − Use pointer arithmetic to traverse the array.

Step 5 − For each element, check if it's a perfect square using sqrt() function.

Step 6 − If it's a perfect square, add it to the sum.

Step 7 − Return the final sum.

Example

The following program demonstrates finding the sum of perfect square elements using pointers −

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

int sumPerfectSquares(int n, int *a) {
    int i, sum = 0, m;
    for (i = 0; i < n; i++) {
        if (*(a + i) >= 0) {  // Only positive numbers can be perfect squares
            m = sqrt(*(a + i));
            if (m * m == *(a + i)) {
                sum += *(a + i);
            }
        }
    }
    return sum;
}

int main() {
    int i, *a, n;
    printf("Enter the size of array: ");
    scanf("%d", &n);
    
    a = (int*)malloc(n * sizeof(int));
    if (a == NULL) {
        printf("Memory allocation failed!<br>");
        return 1;
    }
    
    printf("Enter the elements of array:<br>");
    for (i = 0; i < n; i++) {
        scanf("%d", a + i);
    }
    
    printf("Array elements: ");
    for (i = 0; i < n; i++) {
        printf("%d ", *(a + i));
    }
    printf("<br>");
    
    printf("Sum of perfect square elements is %d<br>", sumPerfectSquares(n, a));
    
    free(a);
    return 0;
}

Enter the size of array: 9
Enter the elements of array:
1
2
3
4
5
9
10
11
16
Array elements: 1 2 3 4 5 9 10 11 16 
Sum of perfect square elements is 30

How It Works

• The function sumPerfectSquares() receives a pointer to the array and its size.
• Pointer arithmetic *(a + i) is used to access array elements instead of a[i].
• For each element, we calculate its square root using sqrt() function.
• We verify if the number is a perfect square by checking if m * m == *(a + i).
• Only non−negative perfect squares (1, 4, 9, 16, 25, etc.) are added to the sum.

Key Points

• Memory is dynamically allocated using malloc() and freed using free().
• Pointer arithmetic *(a + i) provides direct memory access to array elements.
• The sqrt() function returns a floating−point value, so we cast it to integer for comparison.
• Always check for NULL after malloc() to handle memory allocation failures.

Conclusion

Using pointers to find the sum of perfect square elements demonstrates efficient memory access and pointer arithmetic in C. The approach combines mathematical computation with dynamic memory management for flexible array processing.