Home Backend Development Python Tutorial Python内置函数的用法实例教程

Python内置函数的用法实例教程

Jun 16, 2016 am 08:42 AM
python built-in functions usage

本文简单的分析了Python中常用的内置函数的用法,分享给大家供大家参考之用。具体分析如下:

一般来说,在Python中内置了很多有用的函数,我们可以直接调用。

而要调用一个函数,就需要知道函数的名称和参数,比如求绝对值的函数abs,只有一个参数。可以直接从Python的官方网站查看文档:http://docs.python.org/2/library/functions.html#abs

也可以在交互式命令行通过help(abs)查看abs函数的帮助信息。

调用abs函数:

>>> abs(100)
100
>>> abs(-20)
20
>>> abs(12.34)
12.34

Copy after login

调用函数的时候,如果传入的参数数量不对,会报TypeError的错误,并且Python会明确地告诉你:abs()有且仅有1个参数,但给出了两个:

>>> abs(1, 2)
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
TypeError: abs() takes exactly one argument (2 given)

Copy after login

如果传入的参数数量是对的,但参数类型不能被函数所接受,也会报TypeError的错误,并且给出错误信息:str是错误的参数类型:

>>> abs('a')
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
TypeError: bad operand type for abs(): 'str'

Copy after login

而比较函数cmp(x, y)就需要两个参数,如果xy,返回1:

>>> cmp(1, 2)
-1
>>> cmp(2, 1)
1
>>> cmp(3, 3)
0

Copy after login

数据类型转换

Python内置的常用函数还包括数据类型转换函数,比如int()函数可以把其他数据类型转换为整数:

>>> int('123')
123
>>> int(12.34)
12
>>> float('12.34')
12.34
>>> str(1.23)
'1.23'
>>> unicode(100)
u'100'
>>> bool(1)
True
>>> bool('')
False

Copy after login

函数名其实就是指向一个函数对象的引用,完全可以把函数名赋给一个变量,相当于给这个函数起了一个“别名”:

>>> a = abs # 变量a指向abs函数
>>> a(-1) # 所以也可以通过a调用abs函数
1

Copy after login

小结:

调用Python的函数,需要根据函数定义,传入正确的参数。如果函数调用出错,一定要学会看错误信息,所以英文很重要!

希望本文所述实例对大家Python程序设计有所帮助。

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Repo: How To Revive Teammates
4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

How to solve the permissions problem encountered when viewing Python version in Linux terminal? How to solve the permissions problem encountered when viewing Python version in Linux terminal? Apr 01, 2025 pm 05:09 PM

Solution to permission issues when viewing Python version in Linux terminal When you try to view Python version in Linux terminal, enter python...

How to efficiently copy the entire column of one DataFrame into another DataFrame with different structures in Python? How to efficiently copy the entire column of one DataFrame into another DataFrame with different structures in Python? Apr 01, 2025 pm 11:15 PM

When using Python's pandas library, how to copy whole columns between two DataFrames with different structures is a common problem. Suppose we have two Dats...

Python hourglass graph drawing: How to avoid variable undefined errors? Python hourglass graph drawing: How to avoid variable undefined errors? Apr 01, 2025 pm 06:27 PM

Getting started with Python: Hourglass Graphic Drawing and Input Verification This article will solve the variable definition problem encountered by a Python novice in the hourglass Graphic Drawing Program. Code...

Python Cross-platform Desktop Application Development: Which GUI Library is the best for you? Python Cross-platform Desktop Application Development: Which GUI Library is the best for you? Apr 01, 2025 pm 05:24 PM

Choice of Python Cross-platform desktop application development library Many Python developers want to develop desktop applications that can run on both Windows and Linux systems...

Do Google and AWS provide public PyPI image sources? Do Google and AWS provide public PyPI image sources? Apr 01, 2025 pm 05:15 PM

Many developers rely on PyPI (PythonPackageIndex)...

How to efficiently count and sort large product data sets in Python? How to efficiently count and sort large product data sets in Python? Apr 01, 2025 pm 08:03 PM

Data Conversion and Statistics: Efficient Processing of Large Data Sets This article will introduce in detail how to convert a data list containing product information to another containing...

How to optimize processing of high-resolution images in Python to find precise white circular areas? How to optimize processing of high-resolution images in Python to find precise white circular areas? Apr 01, 2025 pm 06:12 PM

How to handle high resolution images in Python to find white areas? Processing a high-resolution picture of 9000x7000 pixels, how to accurately find two of the picture...

How to solve the problem of file name encoding when connecting to FTP server in Python? How to solve the problem of file name encoding when connecting to FTP server in Python? Apr 01, 2025 pm 06:21 PM

When using Python to connect to an FTP server, you may encounter encoding problems when obtaining files in the specified directory and downloading them, especially text on the FTP server...

See all articles