Post Increment/Decrement

Part of the Fundamentals section of Coddy's C++ journey — lesson 19 of 74.

In the previous lesson, we covered the increment (++) and decrement (--) operators. These operators have two forms: prefix and postfix.

The prefix form is written before the variable (e.g., ++x or --x), and the postfix form is written after the variable (e.g., x++ or x--).

Knowing which form to use matters in practice. For example, in a game you might track a player's score with score++ after each hit, or use --lives to immediately reflect a lost life before checking if the game is over. In loops, the choice between prefix and postfix can affect what value is used in an expression before or after the update.

The difference between the two forms is subtle but important:

Prefix form: Increments/decrements the variable and then returns the new value.
Postfix form: Returns the current value of the variable and then increments/decrements it.

Here's an example to illustrate the difference:

int x = 5;
int y = x++;
// y = 5, x = 6 (postfix: y gets the original value, then x is incremented)

int a = 5;
int b = ++a;
// b = 6, a = 6 (prefix: a is incremented first, then b gets the new value)

In the first case, y is assigned the original value of x (5), and then x is incremented to 6. In the second case, a is incremented first, and then its new value (6) is assigned to b.

The same logic applies to the decrement operator:

int x = 5;
int y = x--;
// y = 5, x = 4 (postfix: y gets the original value, then x is decremented)

int a = 5;
int b = --a;
// b = 4, a = 4 (prefix: a is decremented first, then b gets the new value)

Challenge

Beginner

You are given a code with initializations of x, y, and z. (Don't delete these lines!)

Your task is to use the increment/decrement operators to perform the following operations, in this order:

Use the postfix increment operator to assign the current value of x to a and then increment x.
Use the prefix decrement operator to decrement y and assign its new value to b.
Use the postfix decrement operator to assign the current value of z to c and then decrement z.

After performing these operations, print the values of a, b, c, x, y, and z to the console in the following format:

a: [value of a]
b: [value of b]
c: [value of c]
x: [value of x]
y: [value of y]
z: [value of z]

Try it yourself

#include <iostream>

int main() {
    int x = 10;
    int y = 20;
    int z = 30;
    
    int a, b, c;
    
    // Type your code below
    
    
    // Don't change the lines below
    std::cout << "a: " << a << std::endl;
    std::cout << "b: " << b << std::endl;
    std::cout << "c: " << c << std::endl;
    std::cout << "x: " << x << std::endl;
    std::cout << "y: " << y << std::endl;
    std::cout << "z: " << z << std::endl;
    
    return 0;
}