- 2.1 Program Output, the print Statement, and Hello World!
- 2.2 Program Input and the raw_input()Built-in Function
- 2.3 Comments
- 2.4 Operators
- 2.5 Variables and Assignment
- 2.6 Numbers
- 2.7 Strings
- 2.8 Lists and Tuples
- 2.9 Dictionaries
- 2.10 Code Blocks Use Indentation
- 2.11 if Statement
- 2.12 while Loop
- 2.13 for Loop and the range() Built-in Function
- 2.14 List Comprehensions
- 2.15 Files and the open() and file() Built-in Functions
- 2.16 Errors and Exceptions
- 2.17 Functions
- 2.18 Classes
- 2.19 Modules
- 2.20 Useful Functions
- 2.21 Exercises
This chapter is from the book
This chapter is from the book
This chapter is from the book
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!) |