Python 的简单 If 语句问题

Question

Can you guys point out the problem when using "if" repetitively in the codes, for example:

if x == 2:
    do something
if x == 3:
    do something
if x == 4:
    do something

Thanks

Answer 1

This will not cause any errors. Whether you use if or elif will depend on your purpose. Sometimes you want to check several things that are not related. For example, you might have something like

if action is None:
    action = DEFAULT_ACTION
if args is None:
    args = ()

Whether or not action is None will not effect your decision to check if args is None . You might have something else, however, where it makes a difference. For example:

if action is ACTION_JUMP:
    action_jump()
elif distance > 4:
    action_run(distance)

In this case, you don't want action_run() to be called unless the action is not ACTION_JUMP . What you use simply depends on your purpose.

Answer 2

x Traceback (most recent call last): File "", line 1, in x NameError: name 'x' is not defined

If you just assign sth. to x, this won't make errors, but picture: You want sb. input 1-5, but he might input 6. You need to add "else". But you just used so many "if". I recommend using "if---elif(else)---else".