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Arrays and Functions

Explore how to pass arrays to functions in C++ and modify their elements through function calls. Understand why arrays are passed by reference, and see practical examples that demonstrate traversing and updating array values inside functions.

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Passing an array to a function

To pass an array to a function, we just have to specify the array type, followed by an array name and square brackets in the function parameters.

Example program

Let’s write a program that takes an array in its parameters.

In the program, we will traverse the array elements. If the value of an array element is less than 50, we will update the value at that index to -1.

Press the RUN button and see the output!

C++
#include <iostream>
using namespace std;
// print_array function will print the values of an array
void print_array(int number[], int size) {
  for (int i = 0; i < size; i++) {
    cout << number[i] << " ";
  }
  cout << endl;
}
// modify_array function
void modify_array(int number[], int size) {
  // Traverse array
  for (int i = 0; i < size; i++) {
    // If value less tha 50 set it to -1
    if (number[i] < 50)
      number[i] = -1;
  }
  cout << "Values of array inside the function:" << endl;
  // Call print_array function 
  print_array(number,size);
}
// main function
int main() {
  // Initialize size of an array
  int size = 8;
  // Initialize values of array
  int number[size] = {67, 89, 56, 43, 29, 15, 90, 67};
  cout << "Values of array before function call:" << endl;
  // Call print_array function
  print_array(number,size);
  // Call modify_array function
  modify_array(number, size);
  cout << "Values of array after function call:" << endl;
  // Call print_array function
  print_array(number,size);
}

In the code above: ...