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16. Passing Array to a Function in C++ Programming

Passing Array to a Function in C++ Programming

In this article, you'll learn to pass an array to a function in C++. You'll learn to pass both one-dimensional and multi-dimensional arrays.

Passing Array to a Function in C++

Arrays can be passed to a function as an argument. Consider this example to pass one-dimensional array to a function:

Example 1: Passing One-dimensional Array to a Function

C++ Program to display marks of 5 students by passing one-dimensional array to a function.
#include <iostream>
using namespace std;

void display(int marks[5]);

int main()
{
    int marks[5] = {88, 76, 90, 61, 69};
    display(marks);
    return 0;
}

void display(int m[5])
{
    cout << "Displaying marks: "<< endl;

    for (int i = 0; i < 5; ++i)
    {
        cout << "Student "<< i + 1 <<": "<< m[i] << endl;
    }
}
Output
Displaying marks: 
Student 1: 88
Student 2: 76
Student 3: 90
Student 4: 61
Student 5: 69
When an array is passed as an argument to a function, only the name of an array is used as argument.
display(marks);
Also notice the difference while passing array as an argument rather than a variable.
void display(int m[5]);
The argument marks in the above code represents the memory address of first element of array marks[5].
And the formal argument int m[5] in function declaration converts to int* m;. This pointer points to the same address pointed by the array marks.
That's the reason, although the function is manipulated in the user-defined function with different array name m[5], the original array marks is manipulated.
C++ handles passing an array to a function in this way to save memory and time.

Passing Multidimensional Array to a Function

Multidimensional array can be passed in similar way as one-dimensional array. Consider this example to pass two dimensional array to a function:

Example 2: Passing Multidimensional Array to a Function

C++ Program to display the elements of two dimensional array by passing it to a function.
#include <iostream>
using namespace std;

void display(int n[3][2]);

int main()
{
    int num[3][2] = {
        {3, 4},
        {9, 5},
        {7, 1}

    };
    display(num);

    return 0;
}

void display(int n[3][2])
{

    cout << "Displaying Values: " << endl;
    for(int i = 0;  i < 3; ++i)
    {
        for(int j = 0; j < 2; ++j)
        {
            cout << n[i][j] << " ";
        }
    }
}
Output
Displaying Values: 
3 4 9 5 7 1
In the above program, the multi-dimensional array num is passed to the function display().
Inside, display() function, the array n (num) is traversed using a nested for loop.
The program uses 2 for loops to iterate over the elements inside a 2-dimensional array. If it were a 3-dimensional array, you should use 3 for loops.
Finally, all elements are printed onto the screen.
Note: Multidimensional array with dimension more than 2 can be passed in similar way as two dimensional array.


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