[SOLVED] Python - if statements containing multiple boolean conditions

Python - if statements containing multiple boolean conditions - how is flow handled?

I'm curious about how Python handles "if" statements with multiple conditions. Does it evaluate the total boolean expression, or will it "break" from the expression with the first False evaluation?

So, for example, if I have:

if (A and B and C):
   Do_Something()

Will it evaluate "A and B and C" to be True/False (obviously), and then apply the "if" to either enter or not enter Do_Something()?, or will it evaluate each sequentially, and if any turn out to be false it will break.

So, say A is True, B is False.

Will it go: A is true --> keep going, B is false - now break out and not do Do_Something()?

The reason I ask is that in the function I'm working on, I've organised A, B, and C to be functions of increasing computational load, and it (of course) would be a complete waste to run B and C if A is False; and equally C is A is True and B is False). Now, of course, I could simple restructure the code to the following, but I was hoping to use the former if possible:

if (A):
 if (B):
   if (C):
     Do_Something()

Of course, this equally applies to while statements as well.

Any input would be greatly appreciated.

Solution

It's the latter.

if A and B and C:
    Do_Something()

is equivalent to

if A:
    if B:
        if C:
            Do_Something()

This behavior is called short-circuit evaluation.