Python基础语法一

• 安装
• • 还是windows系统，安装2.7。地址：https://www.python.org/downloads/release/python-2712/
  • 注意放到环境变量里
• 运行
• • python file.py
  • sublime text 可以直接运行：ctrl +b 
• helloworld
• • print 'hello'
• 注释
• • 单行：#comment
  • 多行： 连续三个单引号
  • • '''
    • comment line1
    • comment line2
    • comment line3
    • '''
• Python的代码块使用缩进来识别，所以格式非常重要
• 一行语句多行显示 \  ， 同一行显示多行语句 ；
• 数据类型
• • int,long,float,complex
  • bool
  • str
  • list: []表示
  • tuple: ()表示
  • dict:{}表示
  • 后面三个一开始容易混淆，要注意。另外tuple里的元素不可以修改，数据结构和list类似
  • Code:

    ###String
    str = 'Hello World!'
     
    print str        #Hello World!
    print str[0]    #H
    print str[2:5]    #llo
    print str[2:]    #llo World!
    print str * 2    #Hello World!Hello World!
    print str + "TEST"    #Hello World!TEST
     
    ###List
    list = ['runoob', 786, 2.23, 'john', 70.2]
    tinylist = [123, 'john']
     
    print list    #['runoob', 786, 2.23, 'john', 70.2]
    print list[0]    #runoob
    print list[1:3]    #[786, 2.23]
    print list[2:]    #[2.23, 'john', 70.2]
    print tinylist * 2    #[123, 'john', 123, 'john']
    print list + tinylist    #['runoob', 786, 2.23, 'john', 70.2, 123, 'john']
     
    ###Tuple:onlyread
    tuple = ('runoob', 786, 2.23, 'john', 70.2)
    tinytuple = (123, 'john')
     
    print tuple    #('runoob', 786, 2.23, 'john', 70.2)
    print tuple[0]    #runoob
    print tuple[1:3]    #(786, 2.23)
    print tuple[2:]    #(2.23, 'john', 70.2)
    print tinytuple * 2    #(123, 'john', 123, 'john')
    print tuple + tinytuple    #('runoob', 786, 2.23, 'john', 70.2, 123, 'john')
     
    ###Dictionary
    dict = {}
    dict['one'] = "This is one"
    dict[2] = "This is two"
     
    tinydict = {'name':'john', 'code':6734, 'dept':'sales'}
     
    print dict['one']    #This is one
    print dict[2]    #This is two
    print tinydict    #{'dept': 'sales', 'code': 6734, 'name': 'john'}
    print tinydict.keys()    #['dept', 'code', 'name']
    print tinydict.values()    #['sales', 6734, 'john']