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Basic Language Principles

• Python is an interpreted language meaning there is no explicit compilation step.

• The code is simply executed “as-is”. This, coupled with the fact that Python has a simple and easy-to-read syntax means it is an excellent choice for a scripting language.

• It includes all of the features that one expects from a programming language such as basic numerical types, a boolean, a string type and support for various operations upon them. The table below summarises how to use them in Python:

Type	Example	Python code
integer	5	x = 5
float	5.0	x = 5.0
boolean	True/False	x = True
string	‘python’	x = ‘python’ or x = “python”

• The operations are supported as long as it makes sense for that type, e.g. there is no string division but + just means join the two strings together.

• Variable assignment is simple than in other languages as you do not have to declare the type and moreover it can be changed during execution, e.g.

import numpy
# Here x is initialized to 5 and Python then treats this as an integer
x = 5
# It can be incremented and have all of the expected operations applied to it
x += 1

# Later on it can be used for something else
# x is a string and adding a number produces an error
x = "a string"
x + 5

#will give you an error
#Traceback (most recent call last):
# File "<stdin>", line 1, in <module>
#TypeError: cannot concatenate 'str' and 'int' objects

• Comments are signified by the # symbol.

• Errors are signified by things known as Exceptions. In the above example a typical error message is shown which says that an exception of type TypeError occurred and the program needed to terminate (more on handling errors later).

Category:Tested Examples