C program to find the largest among three numbers

This article will teach you how to find the largest or greatest number among three numbers given by the user (at run-time) using and without the ternary operator. Here are the approaches you will go through:

Using if-else-if logic, find the largest of the three numbers

To find the largest number among three given numbers in C programming, first ask the user to enter any three numbers, then use the if-else block to determine which one is the largest, as shown in the program below:

#include<stdio.h>
#include<conio.h>
int main()
{
    int a, b, c, big;
    printf("Enter three numbers: ");
    scanf("%d%d%d", &a, &b, &c);
    if(a>b)
    {
        if(b>c)
            big = a;
        else
        {
            if(c>a)
                big = c;
            else
                big = a;
        }
    }
    else
    {
        if(b>c)
            big = b;
        else
            big = c;
    }
    printf("\nLargest number = %d", big);
    getch();
    return 0;
}

Because the above program was written in the Code::Blocks IDE, you will receive the following output after a successful build and run:

c program find biggest of three numbers

Supply any three numbers, say 3, 1, and 2. Press the ENTER key to see the largest number as given in the second snapshot of the sample run:

c program find largest of three numbers

Here is another sample run:

c program find greatest in three numbers

And here is the last sample run of the above program:

c print largest of three numbers

Here are the cases in which the user can enter the three numbers:

Program Explained

Using if-else logic, find the largest of three numbers.Statement

This program also does the same job but in a simple manner, using an if-else statement in the C language:

#include<stdio.h>
#include<conio.h>
int main()
{
    int a, b, c, big;
    printf("Enter three numbers: ");
    scanf("%d%d%d", &a, &b, &c);
    if(a>b && a>c)
        big = a;
    else if(b>a && b>c)
        big = b;
    else
        big = c;
    printf("\nLargest number = %d", big);
    getch();
    return 0;
}

The above program is a little simpler to create and understand in comparison to the above one. You will see the same output as the previous one.

Using the ternary operator, find the largest of three numbers

Again, I'm going to create the same program using the ternary operator (?:).

#include<stdio.h>
#include<conio.h>
int main()
{
    int num1, num2, num3, large;
    printf("Enter any three numbers: ");
    scanf("%d%d%d", &num1, &num2, &num3);
    large = (num1>num2) ? ((num1>num3)?num1:num3) : ((num2>num3)?num2:num3);
    printf("Largest/Maximum number = %d", large);
    getch();
    return 0;
}

After successfully building and running the above program, here is the first screenshot of the sample run:

largest of three number ternary operator

Now supply any three numbers as input, say 12, 23, and 11, and then press ENTER to see the following output:

largest of three using ternary operator c

Program Explained

Here we have used a nested ternary operator, which is a ternary operator inside a ternary operator.

Find the greatest among three numbers using a function

This is another program doing the same job as all the previous programs did. The only difference with previous programs is that this one is created using a user-defined function, findLarge().

#include<stdio.h>
#include<conio.h>
int findLarge(int, int, int);
int main()
{
    int a, b, c, big;
    printf("Enter three numbers: ");
    scanf("%d%d%d", &a, &b, &c);
    big = findLarge(a, b, c);
    printf("\nLargest number = %d", big);
    getch();
    return 0;
}
int findLarge(int num1, int num2, int num3)
{
    if(num1>num2)
    {
        if(num2>num3)
            return num1;
        else
        {
            if(num3>num1)
                return num3;
            else
                return num1;
        }
    }
    else
    {
        if(num2>num3)
            return num2;
        else
            return num3;
    }
}

Here is the final snapshot of the sample run:

c find largest of three using function

Here, the function takes the three given numbers as its argument and will return the largest one, which will be initialized to the variable big inside the main() function. Print the value of "big," which will hold the largest value among the given three numbers. To learn more about function, you can follow a separate tutorial on it.

The same program in different languages

C Quiz


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