Return array from function

Functions in C can only return scalars, or, with other words, only one value. In order to return arrays we use pointers and return by reference.

This program illustrates how to use pointers to manipulate arrays in C by adding corresponding elements from two input arrays and storing the results in a third array. The addition is performed in a separate function, demonstrating the concept of passing arrays to functions by reference.

#include <stdio.h>
#define SIZE 5 // size of array

// Function declaration
void addArrays(int size, int *array1, int *array2, int *array3);

int main(){

    // Input arrays 
    int array_1[] = {1,2,3,4,5};
    int array_2[] = {10,20,30,40,50};

    // Output array
    int array_3[SIZE];

    // Add array function call
    addArrays(SIZE, array_1, array_2, array_3);

    // Print table header
    printf("Array 1\tArray 2\tArray 3\n");

    // Display array element
    for (int i=0; i<SIZE; i++){
        printf("%d\t%d\t%d\n",array_1[i],array_2[i],array_3[i]);
    }

    return 0;
}

// Function definition
void addArrays(int size, int *array1, int *array2, int *array3){

    for (int i=0; i<SIZE; i++){
        array3[i] = array1[i] + array2[i];
    }

}

Explanation of Code

1. Macro Definition

• #define SIZE 5 defines the size of the arrays used in the program for easy modification and readability.

2. Main Function

• Two input arrays, array_1 and array_2, are initialized with integers.
• An output array, array_3, is declared to store the results of adding corresponding elements of array_1 and array_2.
• The function addArrays is called, passing the size and pointers to the three arrays.
• The program prints a formatted table showing the elements of all three arrays.

3. Function Declaration and Definition

• void addArrays(int size, int *array1, int *array2, int *array3):
  • This function takes the size of the arrays and pointers to the input (array1, array2) and output (array3) arrays.
  • A for loop iterates through the arrays, and the corresponding elements of array1 and array2 are added and stored in array3.

4. Output

The program outputs a table showing the values of the input arrays (array1 and array2) alongside their summed values in array3.

Array 1 Array 2 Array 3
1       10      11
2       20      22
3       30      33
4       40      44
5       50      55

Conclusion

This program highlights the efficiency of using pointers to work with arrays in C. By passing arrays by reference, it avoids the overhead of copying data and allows direct manipulation of memory. This technique is crucial for handling large datasets or implementing high-performance algorithms where resource efficiency is vital. Additionally, the program provides a clear example of modular programming, where reusable functions simplify array operations and improve code clarity.