Comma Operator in C

Prerequisite – Operators in C
The comma operator in C is an operator that allows multiple expressions to be evaluated sequentially in a single statement.

Syntax:
The syntax of the comma operator is as follows:

expr1, expr2, ..., exprn;

Here, expr1, expr2, …, and exprn are expressions that are evaluated in order from left to right. The value of the entire expression is the value of the last expression exprn.

Example:
Here’s an example code that demonstrates the use of the comma operator in C:

#include <stdio.h>

int main() {
    int a = 1, b = 2, c = 3;
    
    // Assign b to a, then assign c to b, and print the value of c
    printf("%d\n", (a = b, b = c, c));
    
    return 0;
}

In this example, we declare three integer variables a, b, and c, with the values 1, 2, and 3, respectively. We then use the comma operator to assign b to a, then assign c to b, and print the value of c.

The expression (a = b, b = c, c) is evaluated from left to right. First, the value of b (2) is assigned to a, then the value of c (3) is assigned to b. Finally, the value of c (3) is returned as the value of the entire expression, which is printed to the console.

The output of this program will be:

3

As you can see, the value of c is printed to the console, which is the value returned by the comma operator.

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