Passing Arrays to Functions in C++

In C++, passing arrays to functions is a common practice that allows for efficient data manipulation. This guide covers the key concepts and methods for doing this effectively.

Key Concepts

• Arrays in C++: An array is a collection of elements of the same type stored in contiguous memory locations.
• Functions: A function is a block of code that performs a specific task and can take parameters, including arrays.

Passing Arrays

1. Passing by Reference

• When passing an array to a function, a reference to the first element is passed, allowing the function to modify the original array.

Example:

#include <iostream>
using namespace std;

void modifyArray(int arr[], int size) {
    for(int i = 0; i < size; i++) {
        arr[i] += 1; // Increment each element by 1
    }
}

int main() {
    int myArray[] = {1, 2, 3, 4, 5};
    int size = sizeof(myArray) / sizeof(myArray[0]);
    
    modifyArray(myArray, size); // Pass array to function
    
    for(int i = 0; i < size; i++) {
        cout << myArray[i] << " "; // Output: 2 3 4 5 6
    }
    return 0;
}

2. Function Declaration

• When declaring a function that accepts an array, use the syntax dataType arrayName[] or dataType* arrayName.
• The size of the array is not required in the function declaration.

Example:

void processArray(int arr[], int size);

3. Size of the Array

• To work with the array's size within the function, pass the size as an additional parameter, as the array does not carry size information.

Important Notes

• Array Decay: An array decays to a pointer when passed to a function, meaning only the address of the first element is passed.
• Limitations: The size of the array cannot be determined from within the function; therefore, always pass the size explicitly.

Summary

Passing arrays to functions in C++ is a straightforward process that facilitates efficient data manipulation. By understanding the reference passing mechanism and the necessity of size parameters, programmers can effectively utilize arrays within functions.