How can I rewrite this diagram in a C++ program?

Thanks for the code 🙂 This makes your mistake obvious.

 while (x <= 1) { cout << x << endl; x = x - 2; }

As long as x <= 1 you execute the while loop.

Example:

x = 2

Output:

//nothing

The program terminates without ever entering the while loop because 2 <= 1 is False. This is true for all x > 1.

x = 1

Output:

1

-1

-3

-4

….

You output the value x, then calculate x = 1 – 2 = -1. Since x is getting smaller and the while loop remains true, you have created an infinite loop. 😉

x = 0

Output:

0

Because of your first if condition, you never get into the while loop. Otherwise, it would have been the next candidate.

——-

What you want is something completely different. 😉

Depending on the input, you want the while to run until x <= 1.

It's good that you're willing to pay more for the test.

1. Receive a number >= 0

 if (x < 0) { cout << "Fehler" << endl; }

Is a good approach to avoid calculating negative values.

2. The main task

IF x <= 1

THEN print X and exit the function

OTHERWISE calculate x = x – 2 and continue

This means while corresponds to the time as long as x > 1.

By the way, with this while the above If query would not be necessary at all.

 while (x > 1){ x = x - 2 } cout << x << endl;

Tip for solving:

Create a table with the values ​​for the variable. Start with the input value.

Then check whether the conditions for if / while / do while are True or False.

Note every change in the value of your variables.