Learn Python by Building Data Science Applications

Understanding if, else, and elif statements

Conditional execution is one of the cornerstones of programming. It allows us to execute one code, but not the other, depending on the condition. This condition is described in Python as an if statement. It is pretty self-explanatory: code within the scope will be executed if the condition is met:

if rain is True:    agenda = 'Stay Home'

Here, if the rain variable is true, the agenda is to stay at home. 

This statement can make functions more flexible. In the following example, if b is equal to 0, we can't use it as a denominator, so we can check the value, and return None instead. As return terminates all the code of the function, the division does not happen:

def percentage(a, b):    if b == 0: return ...