Ternary Operator in C
The ternary operator (?:) in C is a type of conditional operator. The term “ternary” implies that the operator has three operands. The ternary operator is often used to put multiple conditional (if-else) statements in a more compact manner.
Syntax of Ternary Operator in C
The ternary operator is used with the following syntax −
exp1 ? exp2 : exp3
It uses three operands −
- exp1 − A Boolean expression evaluating to true or false
- exp2 − Returned by the ? operator when exp1 is true
- exp3 − Returned by the ? operator when exp1 is false
Example 1: Ternary Operator in C
The following C program uses the ternary operator to check if the value of a variable is even or odd.
#include <stdio.h>
int main(){
int a = 10;
(a % 2 == 0) ? printf("%d is Even \n", a) : printf("%d is Odd \n", a);
return 0;
}
Output
When you run this code, it will produce the following output −
10 is Even
Change the value of “a” to 15 and run the code again. Now you will get the following output −
15 is Odd
Example 2
The conditional operator is a compact representation of if–else construct. We can rewrite the logic of checking the odd/even number by the following code −
#include <stdio.h>
int main(){
int a = 10;
if (a % 2 == 0){
printf("%d is Even\n", a);
}
else{
printf("%d is Odd\n", a);
}
return 0;
}
Output
Run the code and check its output −
10 is Even
Example 3
The following program compares the two variables “a” and “b”, and assigns the one with the greater value to the variable “c”.
#include <stdio.h>
int main(){
int a = 100, b = 20, c;
c = (a >= b) ? a : b;
printf ("a: %d b: %d c: %d\n", a, b, c);
return 0;
}
Output
When you run this code, it will produce the following output −
a: 100 b: 20 c: 100
Example 4
The corresponding code with if–else construct is as follows −
#include <stdio.h>
int main(){
int a = 100, b = 20, c;
if (a >= b){
c = a;
}
else {
c = b;
}
printf ("a: %d b: %d c: %d\n", a, b, c);
return 0;
}
Output
Run the code and check its output −
a: 100 b: 20 c: 100
Example 5
If you need to put multiple statements in the true and/or false operand of the ternary operator, you must separate them by commas, as shown below −
#include <stdio.h>
int main(){
int a = 100, b = 20, c;
c = (a >= b) ? printf ("a is larger "), c = a : printf("b is larger "), c = b;
printf ("a: %d b: %d c: %d\n", a, b, c);
return 0;
}
Output
In this code, the greater number is assigned to “c”, along with printing the appropriate message.
a is larger a: 100 b: 20 c: 20
Example 6
The corresponding program with the use of if–else statements is as follows −
#include <stdio.h>
int main(){
int a = 100, b = 20, c;
if(a >= b){
printf("a is larger \n");
c = a;
}
else{
printf("b is larger \n");
c = b;
}
printf ("a: %d b: %d c: %d\n", a, b, c);
return 0;
}
Output
Run the code and check its output −
a is larger
a: 100 b: 20 c: 100
Nested Ternary Operator
Just as we can use nested if-else statements, we can use the ternary operator inside the True operand as well as the False operand.
exp1 ? (exp2 ? expr3 : expr4) : (exp5 ? expr6: expr7)
First C checks if expr1 is true. If so, it checks expr2. If it is true, the result is expr3; if false, the result is expr4.
If expr1 turns false, it may check if expr5 is true and return expr6 or expr7.
Example 1
Let us develop a C program to determine whether a number is divisible by 2 and 3, or by 2 but not 3, or 3 but not 2, or neither by 2 and 3. We will use nested condition operators for this purpose, as shown in the following code −
#include <stdio.h>
int main(){
int a = 15;
printf("a: %d\n", a);
(a % 2 == 0) ? (
(a%3 == 0)? printf("divisible by 2 and 3") : printf("divisible by 2 but not 3"))
: (
(a%3 == 0)? printf("divisible by 3 but not 2") : printf("not divisible by 2, not divisible by 3")
);
return 0;
}
Output
Check for different values −
a: 15
divisible by 3 but not 2
a: 16
divisible by 2 but not 3
a: 17
not divisible by 2, not divisible by 3
a: 18
divisible by 2 and 3
Example 2
In this program, we have used nested if–else statements for the same purpose instead of conditional operators −
#include <stdio.h>
int main(){
int a = 15;
printf("a: %d\n", a);
if(a % 2 == 0){
if (a % 3 == 0){
printf("divisible by 2 and 3");
}
else {
printf("divisible by 2 but not 3");
}
}
else{
if(a % 3 == 0){
printf("divisible by 3 but not 2");
}
else {
printf("not divisible by 2, not divisible by 3");
}
}
return 0;
}
Output
When you run this code, it will produce the following output −
a: 15
divisible by 3 but not 2