Writing Python Programs

Essentials

• All program files should have the extension

  .py
  

• When developing on Unix, the first line in each Python program should be:

#!/usr/bin env python

• Indentation is a central element of Python syntax, marking code blocks. Code blocks should be indented by four spaces/one tab.
• Indentation must not be used for decorative purposes.

Only one command per line is allowed.

What Python does not have

• Memory allocation.
• Declaration of variables and types.
• Strict object-orientation.
• Line numbers.

Commenting code

• In Python, single lines can be commented by the hash symbol:

# this is a comment.

print a + b # adding the variables.

• Also, multi-line comments can be enclosed by triple quotes:

”””
This is some longer descriptions
that stretches over multiple lines.
”””

• The triple quoted comments can be used to generate documentation automatically.