How to Return Multiple Values from a Function in C | Guide

Introduction

In C, functions can only return a single value directly. However, there are several ways to return multiple values, such as using pointers, structures, arrays, and dynamic memory allocation. This guide explores these methods with examples.

1. Using Pointers (Recommended Approach)

Using pointers is a common way to modify multiple values inside a function and reflect the changes outside.

Example:

cCopyEdit#include <stdio.h>

void getMinMax(int a, int b, int *min, int *max) {
    *min = (a < b) ? a : b;
    *max = (a > b) ? a : b;
}

int main() {
    int x = 10, y = 25, min, max;
    getMinMax(x, y, &min, &max);
    printf("Min: %d, Max: %d\n", min, max);
    return 0;
}

Output:

Min: 10, Max: 25

✅ Best Use Case: When you need to modify multiple variables inside a function.

2. Using Structures

A structure groups multiple values together, allowing a function to return more than one value.

Example:

#include <stdio.h>

typedef struct {
    int quotient;
    int remainder;
} DivisionResult;

DivisionResult divide(int dividend, int divisor) {
    DivisionResult result;
    result.quotient = dividend / divisor;
    result.remainder = dividend % divisor;
    return result;
}

int main() {
    DivisionResult res = divide(10, 3);
    printf("Quotient: %d, Remainder: %d\n", res.quotient, res.remainder);
    return 0;
}

Output:

yamlCopyEditQuotient: 3, Remainder: 1

✅ Best Use Case: When multiple values are logically related, making the code more structured.

3. Using Arrays

An array can store multiple values and be returned via a pointer.

Example:

#include <stdio.h>

void getSquares(int num, int squares[2]) {
    squares[0] = num * num;      // Square
    squares[1] = num * num * num; // Cube
}

int main() {
    int results[2];
    getSquares(4, results);
    printf("Square: %d, Cube: %d\n", results[0], results[1]);
    return 0;
}

Output:

Square: 16, Cube: 64

✅ Best Use Case: When returning multiple values of the same type.

4. Using Dynamic Memory Allocation

Dynamically allocated memory can be used when the number of return values is unknown at compile time.

Example:

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

int* getNumbers() {
    int *arr = (int*)malloc(2 * sizeof(int));
    arr[0] = 10;
    arr[1] = 20;
    return arr;
}

int main() {
    int *nums = getNumbers();
    printf("First: %d, Second: %d\n", nums[0], nums[1]);
    free(nums);  // Free allocated memory
    return 0;
}

Output:

First: 10, Second: 20

✅ Best Use Case: When the number of return values is dynamic or large.

Comparison of Methods

Conclusion

Although C does not support returning multiple values directly, using pointers, structures, arrays, or dynamic memory allocation provides effective alternatives. Choose the method that best suits your use case.