干貨Python3入門教程簡(jiǎn)單但比較不錯(cuò)

1、精選優(yōu)質(zhì)文檔-傾情為你奉上Python已經(jīng)是3.1版本了,與時(shí)俱進(jìn)更新教程.2.5或2.6請(qǐng)看上一篇文章。本文適合有Java編程經(jīng)驗(yàn)的程序員快速熟悉Python本文程序在windows xp+python3.1a1 測(cè)試通過(guò).本文提到的idle指python shell,即安裝python后你在菜單看到的IDLE(python gui)在idle里ctrl+n可以打開(kāi)一個(gè)新窗口,輸入源碼后ctrl+s可以保存,f5運(yùn)行程序.凡打開(kāi)新窗口即指ctrl+n的操作.1 你好復(fù)制代碼代碼如下:#打開(kāi)新窗口,輸入:#! /usr/bin/python# -*- coding: utf8 -*-s1=in

2、put(Input your name:)print(你好,%s % s1)知識(shí)點(diǎn):* input(某字符串)函數(shù):顯示某字符串,并等待用戶輸入.* print()函數(shù):如何打印.* 如何應(yīng)用中文* 如何用多行注釋2 字符串和數(shù)字但有趣的是,在javascript里我們會(huì)理想當(dāng)然的將字符串和數(shù)字連接,因?yàn)槭莿?dòng)態(tài)語(yǔ)言嘛.但在Python里有點(diǎn)詭異,如下:復(fù)制代碼代碼如下:#! /usr/bin/pythona=2b=testc=a+b運(yùn)行這行程序會(huì)出錯(cuò),提示你字符串和數(shù)字不能連接,于是只好用內(nèi)置函數(shù)進(jìn)行轉(zhuǎn)換復(fù)制代碼代碼如下:#! /usr/bin/python#運(yùn)行這行程序會(huì)出錯(cuò),提示你字符串和

3、數(shù)字不能連接,于是只好用內(nèi)置函數(shù)進(jìn)行轉(zhuǎn)換a=2b=testc=str(a)+bd=1111e=a+int(d)#How to print multiply valuesprint (c is %s,e is %i % (c,e)知識(shí)點(diǎn):* 用int和str函數(shù)將字符串和數(shù)字進(jìn)行轉(zhuǎn)換* 打印以#開(kāi)頭,而不是習(xí)慣的/* 打印多個(gè)參數(shù)的方式3 列表復(fù)制代碼代碼如下:#! /usr/bin/python# -*- coding: utf8 -*-#列表類似Javascript的數(shù)組,方便易用#定義元組word=a,b,c,d,e,f,g#如何通過(guò)索引訪問(wèn)元組里的元素a=word2print (a is

4、: +a)b=word1:3print (b is: )print (b) # index 1 and 2 elements of word.c=word:2print (c is: )print (c) # index 0 and 1 elements of word.d=word0:print (d is: )print (d) # All elements of word.#元組可以合并e=word:2+word2:print (e is: )print (e) # All elements of word.f=word-1print (f is: )print (f) # The la

5、st elements of word.g=word-4:-2print (g is: )print (g) # index 3 and 4 elements of word.h=word-2:print (h is: )print (h) # The last two elements.i=word:-2print (i is: )print (i) # Everything except the last two charactersl=len(word)print (Length of word is: + str(l)print (Adds new element)word.appen

6、d(h)print (word)#刪除元素del word0print (word)del word1:3print (word)知識(shí)點(diǎn):* 列表長(zhǎng)度是動(dòng)態(tài)的,可任意添加刪除元素.* 用索引可以很方便訪問(wèn)元素,甚至返回一個(gè)子列表* 更多方法請(qǐng)參考Python的文檔4 字典復(fù)制代碼代碼如下:#! /usr/bin/pythonx=a:aaa,b:bbb,c:12print (xa)print (xb)print (xc)for key in x:print (Key is %s and value is %s % (key,xkey)知識(shí)點(diǎn):* 將他當(dāng)Java的Map來(lái)用即可.5 字符串比起C/

7、C+,Python處理字符串的方式實(shí)在太讓人感動(dòng)了.把字符串當(dāng)列表來(lái)用吧.復(fù)制代碼代碼如下:#! /usr/bin/pythonword=abcdefga=word2print (a is: +a)b=word1:3print (b is: +b) # index 1 and 2 elements of word.c=word:2print (c is: +c) # index 0 and 1 elements of word.d=word0:print (d is: +d) # All elements of word.e=word:2+word2:print (e is: +e) # Al

8、l elements of word.f=word-1print (f is: +f) # The last elements of word.g=word-4:-2print (g is: +g) # index 3 and 4 elements of word.h=word-2:print (h is: +h) # The last two elements.i=word:-2print (i is: +i) # Everything except the last two charactersl=len(word)print (Length of word is: + str(l)中文和

9、英文的字符串長(zhǎng)度是否一樣?復(fù)制代碼代碼如下:#! /usr/bin/python# -*- coding: utf8 -*-s=input(輸入你的中文名,按回車?yán)^續(xù));print (你的名字是 : +s)l=len(s)print (你中文名字的長(zhǎng)度是:+str(l)知識(shí)點(diǎn):類似Java,在python3里所有字符串都是unicode,所以長(zhǎng)度一致.6 條件和循環(huán)語(yǔ)句復(fù)制代碼代碼如下:#! /usr/bin/python#條件和循環(huán)語(yǔ)句x=int(input(Please enter an integer:)if x0:x=0print (Negative changed to zero)e

10、lif x=0:print (Zero)else:print (More)# Loops Lista = cat, window, defenestratefor x in a:print (x, len(x)#知識(shí)點(diǎn):# * 條件和循環(huán)語(yǔ)句# * 如何得到控制臺(tái)輸入7 函數(shù)復(fù)制代碼代碼如下:#! /usr/bin/python# -*- coding: utf8 -*-def sum(a,b):return a+bfunc = sumr = func(5,6)print (r)# 提供默認(rèn)值def add(a,b=2):return a+br=add(1)print (r)r=add(1,5

11、)print (r)一個(gè)好用的函數(shù)#! /usr/bin/python# -*- coding: utf8 -*-# The range() functiona =range (1,10)for i in a:print (i)a = range(-2,-11,-3) # The 3rd parameter stands for stepfor i in a:print (i)知識(shí)點(diǎn):Python 不用來(lái)控制程序結(jié)構(gòu),他強(qiáng)迫你用縮進(jìn)來(lái)寫程序,使代碼清晰.定義函數(shù)方便簡(jiǎn)單方便好用的range函數(shù)8 異常處理復(fù)制代碼代碼如下:#! /usr/bin/pythons=input(Input your

12、 age:)if s =:raise Exception(Input must no be empty.)try:i=int(s)except Exception as err:print(err)finally: # Clean up actionprint(Goodbye!)9 文件處理對(duì)比Java,python的文本處理再次讓人感動(dòng)復(fù)制代碼代碼如下:#! /usr/bin/pythonspath=D:/download/baa.txtf=open(spath,w) # Opens file for writing.Creates this file doesnt exist.f.writ

13、e(First line 1.n)f.writelines(First line 2.)f.close()f=open(spath,r) # Opens file for readingfor line in f:print(每一行的數(shù)據(jù)是:%s%line)f.close()知識(shí)點(diǎn):open的參數(shù):r表示讀,w寫數(shù)據(jù),在寫之前先清空文件內(nèi)容,a打開(kāi)并附加內(nèi)容.打開(kāi)文件之后記得關(guān)閉10 類和繼承復(fù)制代碼代碼如下:class Base:def _init_(self):self.data = def add(self, x):self.data.append(x)def addtwice(self

14、, x):self.add(x)self.add(x)# Child extends Baseclass Child(Base):def plus(self,a,b):return a+boChild =Child()oChild.add(str1)print (oChild.data)print (oChild.plus(2,3)知識(shí)點(diǎn):* self:類似Java的this參數(shù)11 包機(jī)制每一個(gè).py文件稱為一個(gè)module,module之間可以互相導(dǎo)入.請(qǐng)參看以下例子:復(fù)制代碼代碼如下:# a.pydef add_func(a,b):return a+b# b.pyfrom a impor

15、t add_func # Also can be : import aprint (Import add_func from module a)print (Result of 1 plus 2 is: )print (add_func(1,2) # If using import a , then here should be a.add_funcmodule可以定義在包里面.Python定義包的方式稍微有點(diǎn)古怪,假設(shè)我們有一個(gè)parent文件夾,該文件夾有一個(gè)child子文件夾.child中有一個(gè)module a.py . 如何讓Python知道這個(gè)文件層次結(jié)構(gòu)?很簡(jiǎn)單,每個(gè)目錄都放一個(gè)名

16、為_(kāi)init_.py 的文件.該文件內(nèi)容可以為空.這個(gè)層次結(jié)構(gòu)如下所示:parent-_init_.py-child- _init_.py-a.pyb.py那么Python如何找到我們定義的module?在標(biāo)準(zhǔn)包sys中,path屬性記錄了Python的包路徑.你可以將之打印出來(lái):import sysprint(sys.path)通常我們可以將module的包路徑放到環(huán)境變量PYTHONPATH中,該環(huán)境變量會(huì)自動(dòng)添加到sys.path屬性.另一種方便的方法是編程中直接指定我們的module路徑到sys.path 中:復(fù)制代碼代碼如下:import sysimport ossys.path.append(os.getcwd()+parentchild)print(sys.path)from a import add_funcprint (sys.path)print (Import add_func from module a)print (Result of 1 plus 2 i