C Programming: Conditional (Ternary) Operator

Conditional Operator in C Programming

Overview

In C, the conditional operator ?: is a shorthand for an if-else statement. It is called the ternary operator because it operates on three expressions:

Exp1 ? Exp2 : Exp3;

• Exp1: The condition to evaluate.
• Exp2: The result if Exp1 is true (non-zero).
• Exp3: The result if Exp1 is false (zero).

The ternary operator allows for more concise code, especially in simple conditional expressions.

Syntax:

Exp1 ? Exp2 : Exp3;

• If Exp1 evaluates to true (non-zero), Exp2 is executed.
• If Exp1 evaluates to false (zero), Exp3 is executed.

Key Topics:

• The conditional operator ?: is a compact way of writing an if-else statement.
• It is useful when you need to assign values based on a condition in a single line.
• Only one of the two expressions (Exp2 or Exp3) is evaluated based on the condition.

Example 1: Basic Conditional Operator usage

The conditional operator compares two values and assigns the larger one to a variable.

Code:

#include <stdio.h>
int main() {
    int a = 10, b = 20;    
    // Use of the conditional operator
    int max = (a > b) ? a : b;  // If 'a' is greater than 'b', assign 'a' to 'max', else assign 'b'
    
    printf("The maximum value is: %d\n", max);  // Output will be 20
    return 0;
}

Output:

The maximum value is: 20.

Explanation:

• The conditional operator checks if a > b.
• Since this condition is false (10 is not greater than 20), the value of b (20) is assigned to max.

Example 2: Checking for Even or Odd

The conditional operator checks whether a number is even or odd and returns the corresponding result.

Code:

#include <stdio.h>
int main() {
    int num = 5;    
    // Check if the number is even or odd using the conditional operator
    const char *result = (num % 2 == 0) ? "Even" : "Odd";  // If 'num' is divisible by 2, it's even; otherwise, it's odd
    
    printf("%d is %s\n", num, result);  // Output will be 5 is Odd
    return 0;
}

Output:

5 is Odd.

Explanation:

• The conditional operator checks if num % 2 == 0 (whether the number is even).
• Since 5 is not divisible by 2, the string "Odd" is assigned to result.

Example 3: Simplifying Multiple Conditional assignments

Nested conditional operators allow checking for multiple conditions concisely.

Code:

#include <stdio.h>
int main() {
    int num = -10;
    
    // Determine if the number is positive, negative, or zero
    const char *result = (num > 0) ? "Positive" : ((num < 0) ? "Negative" : "Zero");  // Nested conditional operators
    
    printf("%d is %s\n", num, result);  // Output will be -10 is Negative
    return 0;
}

Output:

-10 is Negative.

Explanation:

• The outer conditional checks if num > 0. Since this is false, it moves to the inner conditional.
• The inner conditional checks if num < 0. Since this is true, "Negative" is assigned to result.

Example 4: Conditional Operator in Function return

The conditional operator can be used in functions to return values based on conditions.

Code:

#include <stdio.h>
// Function to return the smaller of two numbers using the conditional operator
int min(int a, int b) {
    return (a < b) ? a : b;  // If 'a' is less than 'b', return 'a', else return 'b'
}
int main() {
    int x = 15, y = 25;    
    printf("The minimum value is: %d\n", min(x, y));  // Output will be 15
    return 0;
}

Output:

The minimum value is: 15.

Explanation:

• The function min uses the conditional operator to return the smaller of the two arguments.
• Since 15 is less than 25, min(x, y) returns 15.

Example 5: Conditional Assignment in expressions

The conditional operator can be used within expressions to simplify logic.

Code:

#include <stdio.h>
int main() {
    int a = 5, b = 10;    
    // Use the conditional operator directly in an expression
    int result = (a < b) ? (a + b) : (a - b);  // If 'a' is less than 'b', result is 'a + b', else it's 'a - b'
    
    printf("Result: %d\n", result);  // Output will be 15
    return 0;
}

Output:

Result: 15.

Explanation:

• The condition a < b is true, so the expression a + b is evaluated.
• Since a is 5 and b is 10, the result is 15.