Python Turtle – How do I stop the turtle at a specific distance or coordinate?

Question:

This is my attempt to make the turtle stop after traveling nearly 400 pixels.

def race():
    while True:
        alex.forward(r_alex)
        a = a + r_alex
        if a > 399.9:
            break

And this is what I got back

UnboundLocalError: local variable 'a' referenced before assignment
Asked By: Quan Bui

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Source

Answers:

The line a = a + r_alex uses a before you actually define a.

I’m guessing a is the turtle’s displacement so perhaps you should try the following:

def race():
    a = 0
    while True:
        alex.forward(r_alex)
        a += r_alex
        if a > 399.9:
            break

Even better:

def race():
    a = 0
    while(a > 399.9):
        alex.forward(r_alex)
        a += r_alex
Answered By: Huey