Python inline if

In coding, you often use branching. A branch in code is executed conditionally. Without branching, you only have a list of instructions and it would always do the same, no matter what happens.

Many programming languages support branching. Python also supports branching. Developers speak of if-statements instead of branching.

Branching in Python

Python does not have a trailing if statement.
In Python there these two kinds of ifs:

• if statements

if condition: statement
if condition:
    code_block

• if expression (python > 2.5)

expression_if_true if condition else expression_if_false

You can check your Python version with

python --version

If-expression

So you can do the following if expression:

a = False
print("hello" if a else "world")

You can change the variable a to see the difference. It will return "hello" or "world" depending on the value of a.

An if-expression must always be an if-else expression, the following will throw an error because else is missing:

a = False

print("hello" if a)

Returns if you run it:

python example.py
  File "example.py", line 4
    print("hello" if a)
                      ^
SyntaxError: invalid syntax

So the else for the if-expression in mandatory.

Related links:

• If expressions
• Learn Python