c - What does the comma operator , do?

Question

What does the , operator do in C?

question from:https://stackoverflow.com/questions/65942759/why-the-output-of-following-code-is-value-of-variable-k

Answer 1

The expression:

(expression1,  expression2)

First expression1 is evaluated, then expression2 is evaluated, and the value of expression2 is returned for the whole expression.