while — Expert Playground

Starts a loop that repeats as long as its condition is true

Python Playground

import dis

# while True is optimized in CPython
def infinite_pattern():
    while True:
        break

def conditional_pattern():
    x = True
    while x:
        break

print("while True bytecode (optimized):")
dis.dis(infinite_pattern)
print("\nwhile x bytecode (not optimized):")
dis.dis(conditional_pattern)

# while True compiles to a simple unconditional jump
# while x compiles to a load + test + conditional jump

Output

Click "Run" to execute your code

CPython optimizes 'while True' into an unconditional jump — there is no condition check at all. 'while variable' adds a load and test on every iteration.

Challenge

Try modifying the code above to explore different behaviors. Can you extend the example to handle a new use case?

View all Expert examples for while