Simple While True Loop And If Statements Fail To NOT Trigger

The relevant code is: while True: command = raw_input('Please enter a command: ') cls() if command == 'quit': cls() quit() break if command

Solution 1:

All of your if statements containing or will run regardless of command's value. This is because a string literal is evaluated as True

The condition if command == "start" or "run" evaluates the value of command first, then evaluates the "truthiness" of the string run. This condition is always satisfied and will always run the code following it.

This should be changed to:

if command == "start" or command =="run":
    do.something()

Solution 2:

Comparisions like

command == "print" or "optimize" or "list"

will always evaluate to True. Python evaluates this as

(command == "print") or bool("optimize") or bool("list") # non-empty strings evaluate to True

Here is how to correct your code:

command == "print" or command == "optimize" or command == "list"

The pythonic way of writing this is:

command in ("print", "optimize", "list")

Solution 3:

Instead of typing:

command == "start" or "run"

You should type:

command == "start" or command == "run"

Because in the first case the or "run" will unconditionally evaulate to True and hence will be executed every time