Day1:The basic of Python

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一、The development of Python

     1、Two types of program:

         Type 1:Python,Java,PHP,C#,Go,ruby,C++…… >>>byte code

         Type 2: C,assembler  >>>machine code

      2、Comparison between the frequencyly used language

          PHP: suitable for website,have limitations

          Python,Java: be suitable for website and background program

               ---Python :high execution,low development 

               ---Java :high development,low execution

           Cause Python is more easier to compile than Java

 二、The type of Python

       Jpython,Ironpython,CPython(commonly used),JavaScript Python,Rubypython

       Pypy:developed by Cpython

三、The basic use of Python

      1、the suffix:

          The suffix is not limited but if without  '.py'  will lead some failure.  

      2、Two executive method:

          (1)、.py route 

        (2)、In the explain device :insert real time and get the real implement results

      3、explain the device route: #!/use/bin/env Python

      4、Python 2 coding: # -*- coding:utf8 -*-

          Eg:AscII 8bits(not enough)  unicode 16bits(a waste of bits); 

          Utf-8 :Can distribute the bytes according to the situation      

      5、execute an operation

           Print: wait until input value and then replace the values

           1) Remind the user input username and password

           2) Insert the username and password

           3)Check

           4)correct:log in;wrong:log failure

      6、Variable :word+number+underline

           1) number can't be the head and don't conclude key words such as:'as','and','from','except','for','exec','del'…

           2) quotation marks:"";'':must be a pair

           3) The algorithm of string: plus and multiple

           Supplement : the algorithm of number:+、_、*、/、%、** 、//

      7、if sentence 

          1) Compared with C :①the strict use of TAB key.②no use of() and {}in some cases

          2) if elif elif else

          3) the use of pass

      8、while sentence

          1) dead circulation :while 1==1

          2) conditional while

      Supplement:

          1) while else

          2) Continue: terminate the current circle and start the next round

              Break:terminate the whole circle

 

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