C++ Program To Find Greatest Of Four Numbers

In this tutorial, we will write a C++ program to find the greatest of four numbers.

For example

a = 10, b = 50, c = 20, d = 25

The greatest number is b 50

a = 35, b = 50, c = 99, d = 2

The greatest number is c 99

Approach 1

The approach is the traditional way of searching for the greatest among four numbers. The if condition checks whether a is greater and then use if-else to check for b, another if-else to check for c, and the last else to print d as the greatest.

Algorithm

✅ START
✅ INPUT FOUR NUMBERS A, B, C, D
✅ IF A > B THEN IF A > C THEN IF A > D THEN A IS THE GREATEST ELSE D IS THE GREATEST
✅ ELSE IF B > C THEN IF B > D THEN B IS THE GREATEST ELSE D IS THE GREATEST
✅ ELSE IF C > D THEN C IS THE GREATEST
✅ ELSE D IS THE GREATEST

C++ Code

Example


#include <bits/stdc++.h>
using namespace std;
void find_greatest(int a, int b, int c, int d)
{
    if (a > b) {
        if (a > c) {
            if (a > d) {
                cout << "a is greatest";
            }
            else {
                cout << "d is greatest";
            }
        }
    }
    else if (b > c) {
        if (b > d) {
            cout << "b is greatest";
        }
        else {
            cout << "d is greatest";
        }
    }
    else if (c > d) {
        cout << "c is greatest";
    }
    else {
        cout << "d is greatest";
    }
}

int main()
{
    int a = 10, b = 50, c = 20, d = 25;
    cout << "a=" << a << " b=" << b << " c=" << c << " d=" << d;
    cout << "\n";
    find_greatest(a, b, c, d);
    a = 35, b = 50, c = 99, d = 2;
    cout << "\n";
    cout << "a=" << a << " b=" << b << " c=" << c << " d=" << d;
    cout << "\n";
    find_greatest(a, b, c, d);

    return 0;
}

Output


a=10 b=50 c=20 d=25
b is greatest
a=35 b=50 c=99 d=2
c is greatest

Approach 2

This approach uses the inbuilt max function.

Here is the syntax of max function

template constexpr const T& max (const T& a, const T& b);

Here, a and b are the numbers to be compared.

Return: Larger of the two values.

For example

std :: max(2,5) will return 5

So, to find out the maximum of 4 numbers, we can use chaining of a max function as follows -

int x = max(a, max(b, max(c, d)));

C++ code

Example


#include <bits/stdc++.h>
using namespace std;
void find_greatest(int a, int b, int c, int d)
{
    int x = max(a, max(b, max(c, d)));
    if (x == a)
        cout << "a is greatest";
    if (x == b)
        cout << "b is greatest";
    if (x == c)
        cout << "c is greatest";
    if (x == d)
        cout << "d is greatest";
}

int main()
{
    int a = 10, b = 50, c = 20, d = 25;
    cout << "a=" << a << " b=" << b << " c=" << c << " d=" << d;
    cout << "\n";
    find_greatest(a, b, c, d);
    a = 35, b = 50, c = 99, d = 2;
    cout << "\n";
    cout << "a=" << a << " b=" << b << " c=" << c << " d=" << d;
    cout << "\n";
    find_greatest(a, b, c, d);

    return 0;
}

Output


a=10 b=50 c=20 d=25
b is greatest
a=35 b=50 c=99 d=2
c is greatest

Input Required