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Learn to Code: C++ for Absolute Beginners

Function Parameters and Return Values

Learn to use parameters and return values with user-defined functions in C++.

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Function with parameters

The parameters are the input values for the function enclosed in (), provided in the function call as arguments. Multiple parameters are separated by , and each parameter must have a data type. The following function receives two int parameters and displays their sum.

void showSum(int a, int b)
{
 cout << a + b << endl;
}

The following is the function call sending 5 and 10 as arguments:

showSum(5,10);
C++
#include <iostream>
using namespace std;
void showSum(int a, int b)
{
  cout << a+b << endl;
}
int main()
{
  showSum(5,10); // Function call
  return 0;
}

Array as a function parameter

An array can be received in a function as a parameter without specifying its size. Therefore, the function should receive the size as a separate parameter.

The following program demonstrates the use of an array as a function parameter:

C++
#include <iostream>
using namespace std;
void getSum(int arr[], int size)
{
  int sum = 0;
  for (int i = 0; i < size; i++)
  {
    sum += arr[i];
  }
  cout << sum << endl;
}
int main()
{
  int nums[4] = {10,20,30,40};
  getSum(nums,4);
  return 0;
}

In the program above, the function receives an array int arr[] and its size int size as parameters. We need the size to traverse through each element of the array. We have used a for loop to calculate the sum of array elements in c and displayed it. In main, we declare an array of 4 elements {10,20,30,40} and pass it ...