Syntax

condition ? expression_if_true : expression_if_false

First the condition is evaluated. A non-zero condition selects the first alternative. A zero condition selects the second alternative. Only the selected alternative is evaluated.

Example: larger value

Write maximum = a > b ? a : b;. If a = 12 and b = 7, the condition is true and maximum becomes 12. If a = 4 and b = 9, the condition is false and maximum becomes 9. Equal values also give the correct maximum.

Example: even or odd

The expression n % 2 == 0 ? "Even" : "Odd" selects the appropriate string for an integer n. It can be passed to printf or puts. Zero is even because its remainder on division by 2 is zero.

Advantages and important points

1. Compact form: Useful for a short choice that produces one value.
2. Readability: Use if-else when the alternatives contain several statements or become difficult to read.
3. Grouping: Nested conditional operators group from right to left. Add parentheses for clarity.
4. Types: The alternative expressions must have types permitted by C; C determines a suitable result type.

Diagram or flowchart

C program and output

/* CodeBhavya | PPS AR25 | Learning example */
#include <stdio.h>
int main(void)
{
    int a = 15, b = 9;
    int larger = a > b ? a : b;
    printf("Larger = %d\n", larger);
    return 0;
}

Larger = 15

Key points

• ?: is an expression that produces a selected value.
• Only one alternative expression is evaluated.