Conditional or Ternary Operator (?:) in C

The conditional operator in C is kind of similar to the if-else statement as it follows the same algorithm as of if-else statement but the conditional operator takes less space and helps to write the if-else statements in the shortest way possible. It is also known as the ternary operator in C as it operates on three operands.

Syntax of Conditional/Ternary Operator in C

The conditional operator can be in the form

variable = Expression1 ? Expression2 : Expression3;

Or the syntax can also be in this form

variable = (condition) ? Expression2 : Expression3;

Or syntax can also be in this form

(condition) ? (variable = Expression2) : (variable = Expression3);

It can be visualized into an if-else statement as: 

if(Expression1)
{
    variable = Expression2;
}
else
{
    variable = Expression3;
}

Since the Conditional Operator '?:' takes three operands to work, hence they are also called ternary operators.

Note: The ternary operator have third most lowest precedence, so we need to use the expressions such that we can avoid errors due to improper operator precedence management.

Working of Conditional/Ternary Operator in C

The working of the conditional operator in C is as follows:

• Step 1: Expression1 is the condition to be evaluated.
• Step 2A: If the condition(Expression1) is True then Expression2 will be executed.
• Step 2B: If the condition(Expression1) is false then Expression3 will be executed.
• Step 3: Results will be returned.

Flowchart of Conditional/Ternary Operator in C

To understand the working better, we can analyze the flowchart of the conditional operator given below.

Examples of C Ternary Operator

Example 1: C Program to Store the greatest of the two Numbers using the ternary operator

// C program to find largest among two
// numbers using ternary operator

#include <stdio.h>

int main()
{
    int m = 5, n = 4;

    (m > n) ? printf("m is greater than n that is %d > %d",
                     m, n)
            : printf("n is greater than m that is %d > %d",
                     n, m);

    return 0;
}

m is greater than n that is 5 > 4

Example 2: C Program to check whether a year is a leap year using ternary operator

// C program to check whether a year is leap year or not
// using ternary operator

#include <stdio.h>

int main()
{
    int yr = 1900;

    (yr%4==0) ? (yr%100!=0? printf("The year %d is a leap year",yr)
     : (yr%400==0 ? printf("The year %d is a leap year",yr)
         : printf("The year %d is not a leap year",yr)))
             : printf("The year %d is not a leap year",yr);
    return 0;
}

//This code is contributed by Susobhan AKhuli

The year 1900 is not a leap year

Conclusion

The conditional operator or ternary operator in C is generally used when we need a short conditional code such as assigning value to a variable based on the condition. It can be used in bigger conditions but it will make the program very complex and unreadable.