What is the function of the postfix negation operator in programming languages?

The postfix decrement operator (usually x-- in languages like Java, C, C++) decreases the value of the variable by 1 but returns its value before the decrement.

Example:

int x = 5;
int y = x--;
// After execution:
// y == 5 (value before decrement)
// x == 4 (value after decrement)

This differs from the prefix operator --x, which first decreases the value and then returns it.