Conditional Operator in C

Conditional operator (?:) is one of the special operators supported by the C language. The conditional operator evaluates an expression and returns one of two values based on whether condition is TRUE or FALSE. 

It has the form:

condition ? result-1 : result-2;

If the condition is TRUE the expression returns result-1 and if not it returns result-2. Example 4.5 – Consider the following example which determines the value of variable “b” based on the whether the given input is greater than 50 or not.

/* Program-4.7 */

#include <stdio.h>

int main()

{

float u,v,t,a;

printf("Enter u (m/s): ");

scanf("%f", &u); //get starting velocity

printf("Enter v (m/s): ");

scanf("%f", &v); //get current velocity

printf("Enter t (s) : ");

scanf("%f", &t); //get time

if(t >= 0)

{

a = (v-u)/t;

printf("acceleration is: %.2f m/s", a);

}

else

printf ("Incorrect time");

return 0;

}

/* Program-4.8 */

#include <stdio.h>

int main()

{

int a,b;

printf("Enter value of a: ");

scanf("%d", &a); //get starting velocity

b = a > 50 ? 1 : 2;

printf("Value of b: %d", b);

return 0;

}

Executing Program-4.8 display the following:

Enter value of a: 51

Value of b: 1

Enter value of a: 45

Value of b: 2

If the input is greater than 50 variable “b” will be assigned “1” and if not it will be assigned “2”. Conditional operator can be used to implement simple if-else constructs. However use of conditional operator is not recommended in modern day programming since it may reduce the readability of the source code.