Learning Python

Library Modules

Currently, there are more than 200 modules in the standard distribution, covering topics such as string and text processing, networking and web tools, system interfaces, database interfaces, serialization, data structures and algorithms, user interfaces, numerical computing, and others. We touch on only the most widely used here and mention some of the more powerful and specialized ones in Chapter 9, and Chapter 10.

Basic String Operations: The string Module

The string module is somewhat of a historical anomaly. If Python were being designed today, chances are many functions currently in the string module would be implemented instead as methods of string objects.^[57] The string module operates on strings. Table 8.4 lists the most useful functions defined in the string module, along with brief descriptions, just to give you an idea as to the module’s purpose. The descriptions given here are not complete; for an exhaustive listing, check the Library Reference or the Python Pocket Reference. Except when otherwise noted, each function returns a string.

Table 8-4. String Module Functions

Function Name	Behavior
atof(string)	Converts a string to a floating point number (see the float built-in): >>> string.atof("1.4") 1.4
atoi(string [, base])	Converts a string to an integer, using the base specified (base 10 by default (see the int built-in): >>> string.atoi("365") 365
atol(string [, base])	Same as atoi, except converts to a long integer (see the long built-in): ...