01
Python在Linux中的常用命令:
进入： python
#可以安装ipython,这样会自带代码提示功能
退出： exit()
进入Python命令行
清屏命令： ctrl + L
查看帮助 help() # ex. help(list)
Python提供内置函数实现进制转换：
bin()
hex()
02
Python文件类型：
1.源代码.py
通过下面的形式可直接运行.py文件：
在demo1.py的文件第一行加上：
#!/usr/bin/python
print 'hello,world'
然后给文件加上可执行型权限：
chmod +x demo1.py
现在可以通过如下形式执行py文件：
./demo1.py
2.字节代码
python源文件经编译后生成的扩展名为 .pyc 的文件
编译方法：
import py_compile
py_compile.compile("demo1.py")
---> 生成demo1.pyc
3.优化代码
经过优化的源文件，扩展名为 ".pyo"
>>>python -O -m py_compile demo1.py
生成demo1.pyo
Python程序示例：
#!/usr/bin/python # import modules used here -- sys is a very standard one import sys # Gather our code in a main() function def main(): print 'Hello there', sys.argv[1] # Command line args are in sys.argv[1], sys.argv[2] ... # sys.argv[0] is the script name itself and can be ignored # Standard boilerplate to call the main() function to begin # the program. if __name__ == '__main__': main()
运行这个程序：
$ ./hello.py Alice
Hello there Alice
函数：
# Defines a "repeat" function that takes 2 arguments. def repeat(s, exclaim): result = s + s + s # can also use "s * 3" which is faster (Why?) #the reason being that * calculates the size of the resulting object once whereas with +, that calculation is made each time + is called if exclaim: result = result + '!!!' return result
函数调用：
def main():
print repeat('Yay', False) ## YayYayYay
print repeat('Woo Hoo', True) ## Woo HooWoo HooWoo Hoo!!!
缩进：
Python使用4个空格作为缩进，具体可以参考如下文档：
see here: http://www.python.org/dev/peps/pep-0008/#indentation
03
Python变量
查看变量内存地址：id(var)
在线帮助技巧：
help(len) -- docs for the built in len function (note here you type "len" not "len()" which would be a call to the function)
help(sys) -- overview docs for the sys module (must do an "import sys" first)
dir(sys) -- dir() is like help() but just gives a quick list of the defined symbols
help(sys.exit) -- docs for the exit() function inside of sys
help('xyz'.split) -- it turns out that the module "str" contains the built-in string code, but if you did not know that, you can call help() just using an example of the sort of call you mean: here 'xyz'.foo meaning the
foo() method that runs on strings
help(list) -- docs for the built in "list" module
help(list.append) -- docs for the append() function in the list modul
04
运算符
raw_input() //从键盘获取值
ex.
a = raw_input("please input a:")
b = raw_input("please input b:")
05
数据类型
type() 可以查看某个字符的数据类型
三重引号：常用来做注释，函数中常用来做doc数据区
”“”
str
“”“
Python字符串：
Python strings are "immutable" which means they cannot be changed after they are created (Java strings also use this immutable style).
s = 'hi' s = 'hi' print s[1] ## i print len(s) ## 2 print s + ' there' ## hi there #print在新行中进行打印 raw = r'this\t\n and that' ## r'str' 表示声明的是一个原始字符串，将会原封不动的打印 print raw ## this\t\n and that multi = """It was the best of times. It was the worst of times.""" pi = 3.14 ##text = 'The value of pi is ' + pi ## NO, does not work text = 'The value of pi is ' + str(pi) ## yes
字符串常用方法：
s.lower(), s.upper() #-- returns the lowercase or uppercase version of the string
s.strip() #-- returns a string with whitespace removed from the start and end
s.isalpha()/s.isdigit()/s.isspace()... #-- tests if all the string chars are in the various character classes
s.startswith('other'), s.endswith('other') #-- tests if the string starts or ends with the given other string
s.find('other') #-- searches for the given other string (not a regular expression) within s, and returns the first index where it begins or -1 if not found
s.replace('old', 'new') #-- returns a string where all occurrences of 'old' have been replaced by 'new'
s.split('delim') #-- returns a list of substrings separated by the given delimiter. The delimiter is not a regular expression, it's just text. 'aaa,bbb,ccc'.split(',') -> ['aaa', 'bbb', 'ccc']. As a convenient special case s.split() (with no arguments) splits on all whitespace chars.
s.join(list) #-- opposite of split(), joins the elements in the given list together using the string as the delimiter. e.g. '---'.join(['aaa', 'bbb', 'ccc']) -> aaa---bbb---ccc
更多内容可以参考如下文档：
http://docs.python.org/2/library/stdtypes.html#string-methods
字符串的格式化输出： % 运算符
# % operator
text = "%d little pigs come out or I'll %s and %s and %s" % (3, 'huff', 'puff', 'blow down')
#因为这行太长，可以用如下的方式：加括号
# add parens to make the long-line work:
text = ("%d little pigs come out or I'll %s and %s and %s" %
(3, 'huff', 'puff', 'blow down'))