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Introduction to Numbers

Numbers provide literal or scalar storage and direct access. Numbers are also an immutable type, meaning that changing or updating its value results in a newly allocated object. This activity is, of course, transparent to both the programmer and the user, so it should not change the way the application is developed.

Python has four types of numbers: "plain" integers, long integers, floating point real numbers, and complex numbers.

How to Create and Assign Numbers (Number Objects)

Creating numbers is as simple as assigning a value to a variable:

						
anInt = 1
1aLong = -9999999999999999L
aFloat = 3.1415926535897932384626433832795
aComplex = 1.23 + 4.56J

					

How to Update Numbers

You can "update" an existing number by (re)assigning a variable to another number. The new value can be related to its previous value or to a completely different number altogether.

						
anInt = anInt + 1
aFloat = 2.718281828

					

How to Remove Numbers

Under normal circumstances, you do not really "remove" a number; you just stop using it! If you really want to delete a reference to a number object, just use the del statement (introduced in Section 3.5.6). You can no longer use the variable name, once removed, unless you assign it to a new object; otherwise, you will cause a NameError exception to occur.

						
					del anInt
del aLong, aFloat, aComplex

					

Okay, now that you have a good idea of how to create and update numbers, let us take a look at Python's four numeric types.


Last updated on 9/14/2001
Core Python Programming, © 2002 Prentice Hall PTR

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© 2002, O'Reilly & Associates, Inc.