Comma Operator in C?

The comma operator in C is denoted by ,. The comma operator in C has the least precedence. The comma operator in C ensures that two or more expressions separated by commas are evaluated one by one from left to right, and the result of the entire expression is the value of the rightmost expression. The comma operator in C is primarily a binary operator that operates on the first available operand, discards the result, evaluates the operands that follow, and then returns the value.

What is the Use of the Comma Operator in C?

To separate two or more expressions we use the comma operator in C. Where expression1 is evaluated first, and after that expression2, and the value of expression2 is returned for the entire expression. In the C programming language, the comma sign serves several purposes: an operator and a separator. As a result, its behavior differs depending on where we put it in a program.

Comma as an Operator

When we want to assign multiple numbers of values to any variable in a program, we use the comma in the form of an operator.

Output:

Explanation: Comma operator in C returns the rightmost operand in the expression and it simply evaluates the rest of the operands. As we can see in the above example first the $x=2$ is executed and then $x+4$. The rightmost expression $x+4$ evaluated to 6 which we could also see in the output.

Comma as a Separator

The comma operator in C can be used as a separator (multiple definitions in a single line) in the program whenever we want to declare multiple variables and provide different parameters in the function.

Output:

Explanation: We can define multiple variables by using a comma as a separator same as we could see in the above example.

Examples of Comma Operators in C

Comma Operator in printf() and scanf()

Here's an example program that uses the comma operator in the printf() and scanf() statement.

Output:

Comma Operator in Multiple Initialization

Here's an example program that uses the comma operator in multiple initializations.

Output:

Explanation: We could use comma operators as int b=(10,20,30) which set the value of b as 30 but we could not use it as int a=10,20,30; as = operator has higher precedence than a comma.

Comma Operator in Updating Values

Here's an example program that uses the comma operator in updating values.

Output:

Explanation: Comma operator is having least precedence over than increment operator as a result first value of i is incremented and then printed.

Comma Operator in if Condition

Here's an example program that uses the comma operator in the conditional statement.

Output:

Explanation: Comma operator inside the if condition works as or operator if the statement is true then it will go in the true block else it will go in the false statement.

Learn More

Learn more about the conditional operator in the C.

• Conditional operator in C