重新梳理Python基礎（3）

1. python輸入raw_input()函數。

a = raw_input() #得到的是字串a = int(raw_input()) #如果想得到int，只能這樣

如果輸入特殊字元，比如\t \n等，會和輸入一樣輸出，%r會輸出\\t、\\n，%s會輸出\t、\n

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print "How old are you?"age = raw_input()print "How tall are you?"height = raw_input()print "How much do you weight?"weight = raw_input()print "So, you are %r old, %r tall and %r heavy." % (age, height, weight)print "So, you are %s old, %s tall and %s heavy." % (age, height, weight)print "So, you are %d old, %d tall and %d heavy." % (int(age), int(height), int(weight))

輸出

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How old are you?\tHow tall are you?\nHow much do you weight?111So, you are '\\t' old, '\\n' tall and '111' heavy.So, you are \t old, \n tall and 111 heavy.

通常都是這麼寫的

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age = raw_input("How old are you?")height = raw_input("How tall are you?")weight = raw_input("How much are you weight?")print "So, you're %r old, %r tall and %r heavy." % (age, height, weight)

input和raw_input的區別

當輸入為純數字時

• input返回的是數實值型別，如int,float
• raw_inpout返回的是字串類型，string類型

輸入字串為運算式

　　input會計算在字串中的數字運算式，而raw_input不會。

　　如輸入 “57 + 3”:

• • 　　input會得到整數60
  • 　　raw_input會得到字串”57 + 3”

其實

def input(prompt):    return (eval(raw_input(prompt)))

2. 在windows中查看doc，可以用如下命令

 python -m pydoc raw_input

3. 運行python指令碼的時候輸入參數，該如何寫。

看代碼

from sys import argvscript, first, second, third = argvprint "The script is called: ", scriptprint "Your first variable is: ", firstprint "Your second variable is: ", secondprint "Your third variable is: ", third

argv類似於java中的main(String[] args)。但是argv需要指定參數個數，並且運行指令碼的時候參數個數要對應，不然會報錯。並且第一個參數是python ex13.py 1 1 1中的ex13.py。

如果參數個數不對，輸出如下：

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E:\SkyDrive\python\the hard way to learn python>python ex13.py 1 2 3 4Traceback (most recent call last):  File "ex13.py", line 2, in <module>    script, first, second, third = argvValueError: too many values to unpack

4. 讀取檔案並列印

在指令碼中讀取檔案，最好把檔案名稱作為指令碼的參數，以下是代碼

from sys import argvscript, filename = argvtxt = open(filename)print txt.read()
txt.close()file_name_again = raw_input("the filename you want to print \n > ")print open(file_name_again).read()

輸出

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E:\SkyDrive\python\the hard way to learn python>python ex15.py ex15_sample.txtThis is stuff I typed into a file.It is really cool stuff.Lots and lots of fun to have in here.the filename you want to print > ex15_sample.txtThis is stuff I typed into a file.It is really cool stuff.Lots and lots of fun to have in here.