Why is a Global Variable not Updating Within a Function, Resulting in an Infinite Loop?

Difference in Variable Scope between Functions and Loops

This question addresses a problem with a global variable not being updated within a function, leading to an infinite loop. The code snippet given is as follows:

<code class="python">done = False

def function():
    for loop:
        code
        if not comply:
            done = True  #let's say that the code enters this if-statement

while done == False:
    function()</code>

The explanation provided suggests that the reason for this issue lies in the scope of variables in functions versus loops. In Python, functions create their own namespace, separate from the global namespace. Therefore, assigning a value to done within the function doesn't modify the global variable done.

To resolve this issue, the answer recommends using the global keyword within the function to explicitly access the global variable:

<code class="python">def function():
    global done  # Access the global variable
    for loop:
        code
        if not comply:
            done = True</code>

By using global, the function is able to modify the global variable done, effectively ending the infinite loop when the if condition is met.

The answer further suggests debugging techniques such as using a debugger or printing statements to trace the flow of execution and identify where the issue arises.

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