How to use the pass statement?

Question

I am in the process of learning Python and I have reached the section about the pass statement. The guide I\'m using defines it as being a Null sta

Answer 1

The best and most accurate way to think of pass is as a way to explicitly tell the interpreter to do nothing. In the same way the following code:

def foo(x,y):
    return x+y

means "if I call the function foo(x, y), sum the two numbers the labels x and y represent and hand back the result",

def bar():
    pass

means "If I call the function bar(), do absolutely nothing."

The other answers are quite correct, but it's also useful for a few things that don't involve place-holding.

For example, in a bit of code I worked on just recently, it was necessary to divide two variables, and it was possible for the divisor to be zero.

c = a / b

will, obviously, produce a ZeroDivisionError if b is zero. In this particular situation, leaving c as zero was the desired behavior in the case that b was zero, so I used the following code:

try:
    c = a / b
except ZeroDivisionError:
    pass

Another, less standard usage is as a handy place to put a breakpoint for your debugger. For example, I wanted a bit of code to break into the debugger on the 20th iteration of a for... in statement. So:

for t in range(25):
    do_a_thing(t)
    if t == 20:
        pass

with the breakpoint on pass.