Conditional Operator in C

The conditional operator in the C programming language

I believe you would have found yourself in this situation one or more times, where you write an if-else code just to execute a single statement. That is kind of a fuss, right? The conditional operator was designed especially for this problem. The conditional operator can help you make decision-making statements in just a single line, whereas an if-else would take more than one line.

The conditional operator takes three operands, so it is a ternary operator. The conditional operator is the only ternary operator available in the C programming language, so the names ternary operator and conditional operator are used alternatively to mean the conditional operator. The operands can be expressions, statements, constants, or variables. Since they always start with a condition as the first operand it is suitably named as conditional operator.

Syntax of conditional operator in C

expression ? statement1 : statement2

The expression will be treated as a logical condition, and any non 0 value will be considered as true, and 0 as false. The statement1 and statement2 can be a statement, an expression, a variable, or a constant. One of the statements will get executed based on the result obtained from the evaluation of the given expression.

Working of conditional operator in C

The conditional operator of the C programming language works as follows:

• The condition is evaluated first and the result of the condition is implicitly converted to bool.
• If the condition evaluates to be true the first statement -- the statement after the question mark will get executed.
• If the condition evaluates to be false then the second statement -- the statement after the colon gets executed.

The result of the conditional operator is the result of one of the two expressions present in the conditional operator. Only one of the last two operands or expressions gets evaluated, the other expression just gets ignored.

The below diagram will help you remember the working of the Conditional Operator in C much more efficiently.

Another version of the conditional operator in C

The conditional operator is a shorter version of the if-else statement for the cases where the if statement would only have one statement. The conditional operator also has a shorter version of itself. This version of the conditional operator was designed to help with the process of checking a condition and assigning a value to a variable, one of the most commonly used use cases in the programming world.

Syntax of the conditional operator in C:

variable = condition ? value1: value2

Working of the conditional operator in C:

The working of this version of the conditional operator is more similar to that of the original conditional operator. The compiler will first evaluate the condition and then store value1 to the variable if the condition is evaluated to be true, and the value2 to will be assigned to the variable in case if the condition evaluates to be false.

The below diagram will help you in remembering the working of the Conditional Operator in C much more efficiently

Some important remarks about the conditional operator.

The first operand of the conditional operator should be of integral or of pointer type. The second and the third operands should be of the same type, if not the C compiler will implicitly convert them to that of the same data type.

Associativity of the conditional operator in C

The Associativity property defines the order in which the operands of the operator gets executed. When an expression has more than one operator in it, and more than one operators have the same precedence, then the order in which the operator gets executed is based on the associativity.
The Associativity of the conditional operator is from Right to Left.

Difference between conditional operator in C and if-else statement in C

The if-else statement and the conditional operator of the C programming language are more similar to each other. They perform almost the same operation -- they check a condition and execute a statement based on the result obtained from the evaluation of the condition. The conditional operator was designed so that the user could write code more efficiently. The conditional operator can be used in the case of an if-else statement if the if-else statement only has one statement to execute. The conditional operator reduces the number of lines of code in a program.
Some noteworthy differences between the conditional operator and the if-else statement of the C programming language are listed in the below tabular column:

Examples of the Conditional operator in C

All these theories can be exhausting, so let's jump into some coding and see some situations where the use of the conditional operator can be extremely helpful.

print whether the given number is odd or even:

#include <stdio.h>
 
int main() {
    int num;  
    scanf("%d", &num);
    (num % 2 == 0)? printf("The given number is even") : printf("The given number is odd");
        
    return 0;
}

Input:

13

Output:

The given number is odd

Input:

6

Output:

The given number is even

Working:

• You will already be familiar with the first three lines of code. They initialize a variable num and read an integer input.
• The conditional operator will first check for the given condition, in the first input i.e., 13 the condition 13 % 2 == 1 evaluates to false, so the second part of the statement gets executed. So the string "The given number is odd" gets printed as the output.
• In the second input i.e., 6 the condition 6 % 2 == 0 evaluates to true, so the first statement gets executed and the string "The given number is even" gets printed as the output.

Frequently Asked Questions (FAQ) about the Conditional operator in C

Let's now answer some of the most Frequently asked questions about the conditional operator.

Is the conditional operator in C and the ternary operator of the C programming language the same?

yes, the conditional operator is sometimes referred to as the ternary operator.

Why is it called a ternary operator?

In the C programming language, the operators are classified as unary, binary, and ternary based on the number of operands they require. In C programming the conditional operator is the only ternary operator, and hence it is also referred to as the ternary operator.

Why is it called a conditional operator in C?

The first operand for the conditional operator is always a condition, so it is called the conditional operator.

Can I use conditional operator in C instead of if statement?

The conditional operator cannot be replaced in the position of the if statement, cause the conditional operator requires three operands so you have no option but to state the else part to execute.