Core Python Programming (2nd Edition)

2.20. Useful Functions
In this chapter, we have seen some useful built-in functions. We summarize them in Table 2.1 and
present a few other useful ones (note that these may not be the full syntax, only what we feel would be
useful for you now).
Table 2.1. Useful Built-In Functions for New Python Programmers
Function Description
dir([obj]) Display attributes of object or the names of global variables if no
parameter given
help([obj]) Display object's documentation string in a pretty-printed format or
enters interactive help if no parameter given
int(obj) Convert object to an integer
len(obj) Return length of object
open(fn, mode) Open file fn with mode ('r' = read, 'w' = write)
range([[start, ]stop[,step]) Return a list of integers that begin at start up to but not including stop
in increments of step; start defaults to 0, and step defaults to 1
raw_input(str) Wait for text input from the user, optional prompt string can be
provided
str(obj) Convert object to a string
type(obj) Return type of object (a type object itself!)