In C, arrays can be passed to functions to perform operations on multiple elements. Since array names act as pointers, passing an array to a function allows direct modification of its elements.

1. Passing an Array to a Function

When passing an array to a function, the function receives a pointer to the first element rather than a copy of the array. This works like a call by reference and allows the function to modify the original array.

As you are passing an address to a function, the function parameter should be either declared as a pointer or

Syntax

void printArray(int arr[], int size) {
    for(int i = 0; i < size; i++) {
        printf("%d ", arr[i]);
    }
}

int main() {
    int numbers[] = {1, 2, 3, 4, 5};
    printArray(numbers, 5);
    return 0;
}

2. Modifying an Array in a Function

Since arrays are passed by reference, changes made inside the function affect the original array.

Example

void modifyArray(int arr[], int size) {
    for(int i = 0; i < size; i++) {
        arr[i] *= 2; // Modifies original array
    }
}

int main() {
    int numbers[] = {1, 2, 3, 4, 5};
    modifyArray(numbers, 5);
    for(int i = 0; i < 5; i++) {
        printf("%d ", numbers[i]); // Output: 2 4 6 8 10
    }
    return 0;
}

3. Passing Multidimensional Arrays

Multidimensional arrays can also be passed to functions. The number of columns must be specified in the function parameter.

Example

void printMatrix(int matrix[][3], int rows) {
    for(int i = 0; i < rows; i++) {
        for(int j = 0; j < 3; j++) {
            printf("%d ", matrix[i][j]);
        }
        printf("\\n");
    }
}

int main() {
    int matrix[2][3] = {{1, 2, 3}, {4, 5, 6}};
    printMatrix(matrix, 2);
    return 0;
}

Summary

• Arrays in C are passed by reference, meaning functions receive a pointer to the first element.
• Modifications made to the array within the function reflect in the original array.
• The array size should be explicitly passed to the function.
• Multidimensional arrays require column size to be specified in function parameters.

Exercises