Python入门教程超详细1小时学会Python（python入门教程(非常详细)免费）-APISpace

Python入门教程超详细1小时学会Python（python入门教程(非常详细)免费）

为什么使用Python 假设我们有这么一项任务:简单测试局域网中的电脑是否连通.这些电脑的ip范围从192.168.0.101到192.168.0.200.

思路:用shell编程.(Linux通常是bash而Windows是批处理脚本).例如,在Windows上用ping ip 的命令依次测试各个机器并得到控制台输出.由于ping通的时候控制台文本通常是"Reply from ... " 而不通的时候文本是"time out ... " ,所以,在结果中进行字符串查找,即可知道该机器是否连通.

实现:Java代码如下:

String cmd="cmd.exe ping ";

String ipprefix="192.168.10.";

int begin=101;

int end=200;

Process p=null;

for(int i=begin;i

p= Runtime.getRuntime().exec(cmd+i);

String line = null;

BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));

while((line = reader.readLine()) != null)

{

//Handling line , may logs it.

}

reader.close();

p.destroy();

}

这段代码运行得很好,问题是为了运行这段代码,你还需要做一些额外的工作.这些额外的工作包括: 编写一个类文件编写一个main方法将之编译成字节代码由于字节代码不能直接运行,你需要再写个小小的bat或者bash脚本来运行. 当然,用C/C++同样能完成这项工作.但C/C++不是跨平台语言.在这个足够简单的例子中也许看不出C/C++和Java实现的区别,但在一些更为复杂的场景,比如要将连通与否的信息记录到网络数据库.由于Linux和Windows的网络接口实现方式不同,你不得不写两个函数的版本.用Java就没有这样的顾虑.

同样的工作用Python实现如下:

import subprocess

cmd="cmd.exe"

begin=101

end=200

while begin

p=subprocess.Popen(cmd,shell=True,stdout=subprocess.PIPE,

stdin=subprocess.PIPE,

stderr=subprocess.PIPE)

p.stdin.write("ping 192.168.1."+str(begin)+"\n")

p.stdin.close()

p.wait()

print "execution result: %s"%p.stdout.read()

对比Java,Python的实现更为简洁,你编写的时间更快.你不需要写main函数,并且这个程序保存之后可以直接运行.另外,和Java一样,Python也是跨平台的.

有经验的C/Java程序员可能会争论说用C/Java写会比Python写得快.这个观点见仁见智.我的想法是当你同时掌握Java和Python之后,你会发现用Python写这类程序的速度会比Java快上许多.例如操作本地文件时你仅需要一行代码而不需要Java的许多流包装类.各种语言有其天然的适合的应用范围.用Python处理一些简短程序类似与操作系统的交互编程工作最省时省力.

Python应用场合足够简单的任务,例如一些shell编程.如果你喜欢用Python设计大型商业网站或者设计复杂的游戏,悉听尊便.

2 快速入门 2.1 Hello world 安装完Python之后(我本机的版本是2.5.4),打开IDLE(Python GUI) , 该程序是Python语言解释器,你写的语句能够立即运行.我们写下一句著名的程序语句:

print "Hello,world!"

并按回车.你就能看到这句被K&R引入到程序世界的名言.

在解释器中选择"File"--"New Window" 或快捷键 Ctrl+N , 打开一个新的编辑器.写下如下语句:

print "Hello,world!" raw_input("Press enter key to close this window");

保存为a.py文件.按F5,你就可以看到程序的运行结果了.这是Python的第二种运行方式.

找到你保存的a.py文件,双击.也可以看到程序结果.Python的程序能够直接运行,对比Java,这是一个优势.

2.2 国际化支持我们换一种方式来问候世界.新建一个编辑器并写如下代码:

print "欢迎来到奥运中国!" raw_input("Press enter key to close this window");

在你保存代码的时候,Python会提示你是否改变文件的字符集,结果如下:

# -*- coding: cp936 -*-

print "欢迎来到奥运中国!"

raw_input("Press enter key to close this window");

将该字符集改为我们更熟悉的形式:

-- coding: GBK --

print "欢迎来到奥运中国!" # 使用中文的例子

raw_input("Press enter key to close this window");

程序一样运行良好.

2.3 方便易用的计算器用微软附带的计算器来计数实在太麻烦了.打开Python解释器,直接进行计算:

a=100.0

b=201.1

c=2343

print (a+b+c)/c

2.4 字符串,ASCII和UNICODE

可以如下打印出预定义输出格式的字符串:

print """

Usage: thingy [OPTIONS]

-h Display this usage message

-H hostname Hostname to connect to

"""

字符串是怎么访问的?请看这个例子:

word="abcdefg"

a=word[2]

print "a is: "+a

b=word[1:3]

print "b is: "+b # index 1 and 2 elements of word.

c=word[:2]

print "c is: "+c # index 0 and 1 elements of word.

d=word[0:]

print "d is: "+d # All elements of word.

e=word[:2]+word[2:]

print "e is: "+e # All elements of word.

f=word[-1]

print "f is: "+f # The last elements of word.

g=word[-4:-2]

print "g is: "+g # index 3 and 4 elements of word.

h=word[-2:]

print "h is: "+h # The last two elements.

i=word[:-2]

print "i is: "+i # Everything except the last two characters

l=len(word)

print "Length of word is: "+ str(l)

请注意ASCII和UNICODE字符串的区别:

print "Input your Chinese name:"

s=raw_input("Press enter to be continued");

print "Your name is : " +s;

l=len(s)

print "Length of your Chinese name in asc codes is:"+str(l);

a=unicode(s,"GBK")

l=len(a)

print "I'm sorry we should use unicode char!Characters number of your Chinese \

name in unicode is:"+str(l);

2.5 使用List 类似Java里的List,这是一种方便易用的数据类型:

word=['a','b','c','d','e','f','g']

a=word[2]

print "a is: "+a

b=word[1:3]

print "b is: "

print b # index 1 and 2 elements of word.

c=word[:2]

print "c is: "

print c # index 0 and 1 elements of word.

d=word[0:]

print "d is: "

print d # All elements of word.

e=word[:2]+word[2:]

print "e is: "

print e # All elements of word.

f=word[-1]

print "f is: "

print f # The last elements of word.

g=word[-4:-2]

print "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[:-2]

print "i is: "

print i # Everything except the last two characters

l=len(word)

print "Length of word is: "+ str(l)

print "Adds new element"

word.append('h')

print word

2.6 条件和循环语句 # Multi-way decision x=int(raw_input("Please enter an integer:")) if x<0: x=0 print "Negative changed to zero"

elif x==0:

print "Zero"

else:

print "More"

# Loops List

a = ['cat', 'window', 'defenestrate']

for x in a:

print x, len(x)

2.7 如何定义函数 # Define and invoke function. def sum(a,b): return a+b

func = sum

r = func(5,6)

print r

# Defines function with default argument

def add(a,b=2):

return a+b

r=add(1)

print r

r=add(1,5)

print r

并且,介绍一个方便好用的函数:

# The range() function

a =range(5,10)

print a

a = range(-2,-7)

print a

a = range(-7,-2)

print a

a = range(-2,-11,-3) # The 3rd parameter stands for step

print a

2.8 文件I/O spath="D:/download/baa.txt" f=open(spath,"w") # Opens file for writing.Creates this file doesn't exist. f.write("First line 1.\n") f.writelines("First line 2.")

f.close()

f=open(spath,"r") # Opens file for reading

for line in f:

print line

f.close()

2.9 异常处理

s=raw_input("Input your age:")

if s =="":

raise Exception("Input must no be empty.")

try:

i=int(s)

except ValueError:

print "Could not convert data to an integer."

except:

print "Unknown exception!"

else: # It is useful for code that must be executed if the try clause does not raise an exception

print "You are %d" % i," years old"

finally: # Clean up action

print "Goodbye!"

2.10 类和继承 class Base: def init(self): self.data = [] def add(self, x): self.data.append(x) def addtwice(self, x): self.add(x) self.add(x)

# Child extends Base

class Child(Base):

def plus(self,a,b):

return a+b

oChild =Child()

oChild.add("str1")

print oChild.data

print oChild.plus(2,3)

2.11 包机制每一个.py文件称为一个module,module之间可以互相导入.请参看以下例子: # a.py def add_func(a,b): return a+b

# b.py

from a import add_func # Also can be : import a

print "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_func"

module可以定义在包里面.Python定义包的方式稍微有点古怪,假设我们有一个parent文件夹,该文件夹有一个child子文件夹.child中有一个module a.py . 如何让Python知道这个文件层次结构?很简单,每个目录都放一个名为_init_.py 的文件.该文件内容可以为空.这个层次结构如下所示:

parent

--__init_.py

--child

-- __init_.py

--a.py

b.py

那么Python如何找到我们定义的module?在标准包sys中,path属性记录了Python的包路径.你可以将之打印出来:

import sys

print sys.path

通常我们可以将module的包路径放到环境变量PYTHONPATH中,该环境变量会自动添加到sys.path属性.另一种方便的方法是编程中直接指定我们的module路径到sys.path 中:

import sys

sys.path.append('D:\\download')

from parent.child.a import add_func

print sys.path

print "Import add_func from module a"

print "Result of 1 plus 2 is: "

print add_func(1,2)

p= Runtime.getRuntime().exec(cmd+i);

String line = null;

BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));

while((line = reader.readLine()) != null)

{

//Handling line , may logs it.

}

reader.close();

p.destroy();

}

同样的工作用Python实现如下:

import subprocess

cmd="cmd.exe"

begin=101

end=200

while begin

p=subprocess.Popen(cmd,shell=True,stdout=subprocess.PIPE,

stdin=subprocess.PIPE,

stderr=subprocess.PIPE)

p.stdin.write("ping 192.168.1."+str(begin)+"\n")

p.stdin.close()

p.wait()

print "execution result: %s"%p.stdout.read()

对比Java,Python的实现更为简洁,你编写的时间更快.你不需要写main函数,并且这个程序保存之后可以直接运行.另外,和Java一样,Python也是跨平台的.

Python应用场合足够简单的任务,例如一些shell编程.如果你喜欢用Python设计大型商业网站或者设计复杂的游戏,悉听尊便.

print "Hello,world!"

并按回车.你就能看到这句被K&R引入到程序世界的名言.

在解释器中选择"File"--"New Window" 或快捷键 Ctrl+N , 打开一个新的编辑器.写下如下语句:

print "Hello,world!" raw_input("Press enter key to close this window");

保存为a.py文件.按F5,你就可以看到程序的运行结果了.这是Python的第二种运行方式.

找到你保存的a.py文件,双击.也可以看到程序结果.Python的程序能够直接运行,对比Java,这是一个优势.

2.2 国际化支持我们换一种方式来问候世界.新建一个编辑器并写如下代码:

print "欢迎来到奥运中国!" raw_input("Press enter key to close this window");

在你保存代码的时候,Python会提示你是否改变文件的字符集,结果如下:

# -*- coding: cp936 -*-

print "欢迎来到奥运中国!"

raw_input("Press enter key to close this window");

将该字符集改为我们更熟悉的形式:

-- coding: GBK --

print "欢迎来到奥运中国!" # 使用中文的例子

raw_input("Press enter key to close this window");

程序一样运行良好.

2.3 方便易用的计算器用微软附带的计算器来计数实在太麻烦了.打开Python解释器,直接进行计算:

a=100.0

b=201.1

c=2343

print (a+b+c)/c

2.4 字符串,ASCII和UNICODE

可以如下打印出预定义输出格式的字符串:

print """

Usage: thingy [OPTIONS]

-h Display this usage message

-H hostname Hostname to connect to

"""

字符串是怎么访问的?请看这个例子:

word="abcdefg"

a=word[2]

print "a is: "+a

b=word[1:3]

print "b is: "+b # index 1 and 2 elements of word.

c=word[:2]

print "c is: "+c # index 0 and 1 elements of word.

d=word[0:]

print "d is: "+d # All elements of word.

e=word[:2]+word[2:]

print "e is: "+e # All elements of word.

f=word[-1]

print "f is: "+f # The last elements of word.

g=word[-4:-2]

print "g is: "+g # index 3 and 4 elements of word.

h=word[-2:]

print "h is: "+h # The last two elements.

i=word[:-2]

print "i is: "+i # Everything except the last two characters

l=len(word)

print "Length of word is: "+ str(l)

请注意ASCII和UNICODE字符串的区别:

print "Input your Chinese name:"

s=raw_input("Press enter to be continued");

print "Your name is : " +s;

l=len(s)

print "Length of your Chinese name in asc codes is:"+str(l);

a=unicode(s,"GBK")

l=len(a)

print "I'm sorry we should use unicode char!Characters number of your Chinese \

name in unicode is:"+str(l);

2.5 使用List 类似Java里的List,这是一种方便易用的数据类型:

word=['a','b','c','d','e','f','g']

a=word[2]

print "a is: "+a

b=word[1:3]

print "b is: "

print b # index 1 and 2 elements of word.

c=word[:2]

print "c is: "

print c # index 0 and 1 elements of word.

d=word[0:]

print "d is: "

print d # All elements of word.

e=word[:2]+word[2:]

print "e is: "

print e # All elements of word.

f=word[-1]

print "f is: "

print f # The last elements of word.

g=word[-4:-2]

print "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[:-2]

print "i is: "

print i # Everything except the last two characters

l=len(word)

print "Length of word is: "+ str(l)

print "Adds new element"

word.append('h')

print word

2.6 条件和循环语句 # Multi-way decision x=int(raw_input("Please enter an integer:")) if x<0: x=0 print "Negative changed to zero"

elif x==0:

print "Zero"

else:

print "More"

# Loops List

a = ['cat', 'window', 'defenestrate']

for x in a:

print x, len(x)

2.7 如何定义函数 # Define and invoke function. def sum(a,b): return a+b

func = sum

r = func(5,6)

print r

# Defines function with default argument

def add(a,b=2):

return a+b

r=add(1)

print r

r=add(1,5)

print r

并且,介绍一个方便好用的函数:

# The range() function

a =range(5,10)

print a

a = range(-2,-7)

print a

a = range(-7,-2)

print a

a = range(-2,-11,-3) # The 3rd parameter stands for step

print a

2.8 文件I/O spath="D:/download/baa.txt" f=open(spath,"w") # Opens file for writing.Creates this file doesn't exist. f.write("First line 1.\n") f.writelines("First line 2.")

f.close()

f=open(spath,"r") # Opens file for reading

for line in f:

print line

f.close()

2.9 异常处理

s=raw_input("Input your age:")

if s =="":

raise Exception("Input must no be empty.")

try:

i=int(s)

except ValueError:

print "Could not convert data to an integer."

except:

print "Unknown exception!"

else: # It is useful for code that must be executed if the try clause does not raise an exception

print "You are %d" % i," years old"

finally: # Clean up action

print "Goodbye!"

2.10 类和继承 class Base: def init(self): self.data = [] def add(self, x): self.data.append(x) def addtwice(self, x): self.add(x) self.add(x)

# Child extends Base

class Child(Base):

def plus(self,a,b):

return a+b

oChild =Child()

oChild.add("str1")

print oChild.data

print oChild.plus(2,3)

2.11 包机制每一个.py文件称为一个module,module之间可以互相导入.请参看以下例子: # a.py def add_func(a,b): return a+b

# b.py

from a import add_func # Also can be : import a

print "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_func"

parent

--__init_.py

--child

-- __init_.py

--a.py

b.py

那么Python如何找到我们定义的module?在标准包sys中,path属性记录了Python的包路径.你可以将之打印出来:

import sys

print sys.path

import sys

sys.path.append('D:\\download')

from parent.child.a import add_func

print sys.path

print "Import add_func from module a"

print "Result of 1 plus 2 is: "

print add_func(1,2)

p=subprocess.Popen(cmd,shell=True,stdout=subprocess.PIPE,

stdin=subprocess.PIPE,

stderr=subprocess.PIPE)

p.stdin.write("ping 192.168.1."+str(begin)+"\n")

p.stdin.close()

p.wait()

print "execution result: %s"%p.stdout.read()

对比Java,Python的实现更为简洁,你编写的时间更快.你不需要写main函数,并且这个程序保存之后可以直接运行.另外,和Java一样,Python也是跨平台的.

Python应用场合足够简单的任务,例如一些shell编程.如果你喜欢用Python设计大型商业网站或者设计复杂的游戏,悉听尊便.

print "Hello,world!"

并按回车.你就能看到这句被K&R引入到程序世界的名言.

在解释器中选择"File"--"New Window" 或快捷键 Ctrl+N , 打开一个新的编辑器.写下如下语句:

print "Hello,world!" raw_input("Press enter key to close this window");

保存为a.py文件.按F5,你就可以看到程序的运行结果了.这是Python的第二种运行方式.

找到你保存的a.py文件,双击.也可以看到程序结果.Python的程序能够直接运行,对比Java,这是一个优势.

2.2 国际化支持我们换一种方式来问候世界.新建一个编辑器并写如下代码:

print "欢迎来到奥运中国!" raw_input("Press enter key to close this window");

在你保存代码的时候,Python会提示你是否改变文件的字符集,结果如下:

# -*- coding: cp936 -*-

print "欢迎来到奥运中国!"

raw_input("Press enter key to close this window");

将该字符集改为我们更熟悉的形式:

-- coding: GBK --

print "欢迎来到奥运中国!" # 使用中文的例子

raw_input("Press enter key to close this window");

程序一样运行良好.

2.3 方便易用的计算器用微软附带的计算器来计数实在太麻烦了.打开Python解释器,直接进行计算:

a=100.0

b=201.1

c=2343

print (a+b+c)/c

2.4 字符串,ASCII和UNICODE

可以如下打印出预定义输出格式的字符串:

print """

Usage: thingy [OPTIONS]

-h Display this usage message

-H hostname Hostname to connect to

"""

字符串是怎么访问的?请看这个例子:

word="abcdefg"

a=word[2]

print "a is: "+a

b=word[1:3]

print "b is: "+b # index 1 and 2 elements of word.

c=word[:2]

print "c is: "+c # index 0 and 1 elements of word.

d=word[0:]

print "d is: "+d # All elements of word.

e=word[:2]+word[2:]

print "e is: "+e # All elements of word.

f=word[-1]

print "f is: "+f # The last elements of word.

g=word[-4:-2]

print "g is: "+g # index 3 and 4 elements of word.

h=word[-2:]

print "h is: "+h # The last two elements.

i=word[:-2]

print "i is: "+i # Everything except the last two characters

l=len(word)

print "Length of word is: "+ str(l)

请注意ASCII和UNICODE字符串的区别:

print "Input your Chinese name:"

s=raw_input("Press enter to be continued");

print "Your name is : " +s;

l=len(s)

print "Length of your Chinese name in asc codes is:"+str(l);

a=unicode(s,"GBK")

l=len(a)

print "I'm sorry we should use unicode char!Characters number of your Chinese \

name in unicode is:"+str(l);

2.5 使用List 类似Java里的List,这是一种方便易用的数据类型:

word=['a','b','c','d','e','f','g']

a=word[2]

print "a is: "+a

b=word[1:3]

print "b is: "

print b # index 1 and 2 elements of word.

c=word[:2]

print "c is: "

print c # index 0 and 1 elements of word.

d=word[0:]

print "d is: "

print d # All elements of word.

e=word[:2]+word[2:]

print "e is: "

print e # All elements of word.

f=word[-1]

print "f is: "

print f # The last elements of word.

g=word[-4:-2]

print "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[:-2]

print "i is: "

print i # Everything except the last two characters

l=len(word)

print "Length of word is: "+ str(l)

print "Adds new element"

word.append('h')

print word

2.6 条件和循环语句 # Multi-way decision x=int(raw_input("Please enter an integer:")) if x<0: x=0 print "Negative changed to zero"

elif x==0:

print "Zero"

else:

print "More"

# Loops List

a = ['cat', 'window', 'defenestrate']

for x in a:

print x, len(x)

2.7 如何定义函数 # Define and invoke function. def sum(a,b): return a+b

func = sum

r = func(5,6)

print r

# Defines function with default argument

def add(a,b=2):

return a+b

r=add(1)

print r

r=add(1,5)

print r

并且,介绍一个方便好用的函数:

# The range() function

a =range(5,10)

print a

a = range(-2,-7)

print a

a = range(-7,-2)

print a

a = range(-2,-11,-3) # The 3rd parameter stands for step

print a

2.8 文件I/O spath="D:/download/baa.txt" f=open(spath,"w") # Opens file for writing.Creates this file doesn't exist. f.write("First line 1.\n") f.writelines("First line 2.")

f.close()

f=open(spath,"r") # Opens file for reading

for line in f:

print line

f.close()

2.9 异常处理

s=raw_input("Input your age:")

if s =="":

raise Exception("Input must no be empty.")

try:

i=int(s)

except ValueError:

print "Could not convert data to an integer."

except:

print "Unknown exception!"

else: # It is useful for code that must be executed if the try clause does not raise an exception

print "You are %d" % i," years old"

finally: # Clean up action

print "Goodbye!"

2.10 类和继承 class Base: def init(self): self.data = [] def add(self, x): self.data.append(x) def addtwice(self, x): self.add(x) self.add(x)

# Child extends Base

class Child(Base):

def plus(self,a,b):

return a+b

oChild =Child()

oChild.add("str1")

print oChild.data

print oChild.plus(2,3)

2.11 包机制每一个.py文件称为一个module,module之间可以互相导入.请参看以下例子: # a.py def add_func(a,b): return a+b

# b.py

from a import add_func # Also can be : import a

print "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_func"

parent

--__init_.py

--child

-- __init_.py

--a.py

b.py

那么Python如何找到我们定义的module?在标准包sys中,path属性记录了Python的包路径.你可以将之打印出来:

import sys

print sys.path

import sys

sys.path.append('D:\\download')

from parent.child.a import add_func

print sys.path

print "Import add_func from module a"

print "Result of 1 plus 2 is: "

print add_func(1,2)

Python基础：双下方法（python基础题库刷题训练）

278 2022-07-28

Python入门教程超详细1小时学会Python（python入门教程(非常详细)免费）

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