Python Programming with Design Patterns

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Making Decisions in Python

The familiar if-else C and Java syntax has its analog in Python. However, it is important to note that any conditional statement ends with a colon and that all the statements that are to be executed must be indented by four spaces. Many Python development environments allow you to use tabs to create this indentation:

if y > 0:
    z = x / y
    print("z = ",  z)

If you want to carry out either one set of statements or another depending on a single condition, you should use the else clause along with the if statement:

if y > 0:
    z = x / y
else:
    z = 0

If the else clause contains multiple statements, they must be indented, as in the previous example. Note that the else clause also requires a colon to set it off.

Python does ...