need understanding of while loop condition (see comment)

Question

while (x >= 1000)
{
    cout << "M";
    x -= 1000;
}

Can someone explain to me how this while loop works? I understand the condition is for x is greater or equal to 1000, it will print out 'M'.

The part after that is what I actually don't understand, is it saying that it will keep subtracting a thousand from X and keep printing until the condition is false?

Answer 1

while (x >= 1000)   //x is greater than or equal to 1000
{                   //executes loop if condition true, else the statement after the loop block
    cout << "M";  // print M
    x -= 1000;    // x = x-1000
}                  //goes back to condition checking

Answer 2

Yes, that is exactly what it will do.

This translates roughly into:

While x is greater than or equal to 1000, do what is in the code block (over and over until the condition fails)

The code block then prints M and sets x equal to itself minus 1000. (x -= 1000 is the same as x = x - 1000

Hypothetical:

x = 3000
x is greater than 1000
print M
x is set to 2000
loop resets and checks x...passes test
print M
x is set to 1000
loop resets and checks x...passes test because of = portion
print M
x is set to 0
loop resets and checks x...fails
moves to the code after the while code block

Answer 3

The program appears to be an inefficient way of writing

x %= 1000;

which is x = x%1000, where % is the modulus operator.

Your code reaches the same result by subsequent substraction, and stops when x<1000.

Answer 4

Yes.

it saying that it will keep subtracting a thousand from X and keep printing until the condition is false

Answer 5

You are right!

x-=1000; 

is actually

x=x-1000;