Article From:https://www.cnblogs.com/J-7-H-2-F-7/p/9127744.html

  Operator and coding

Formatted output

   1  .Input name, age, job, hobby.

        Output: info of Mary

                  Name  : Mary

                  Age   : 18

                  Job  : Teacher  

                   Hobbie  :sing

                      ———————-end————————-

 

          eg:   name = input (“Name  : “)

                  age = input (“Age : “)

                  job = inut (“Job  : “)

                  hobby = input (“Hobbt  : “)

info = ‘’‘

—————————-  info of %s ————–  -# Each%s is a placeholder, (name)

Name  : %s   #Representing name

Age  : %s  #Representing age

Job  : %s #Representing job

Hobby  : %s   #Representing hobbie

——————————– end ———————-

”’% (name,name,age,job,hobbie)   #  The% of this line is to associate the preceding string with variables after parenthesis.

print(info)

   2.  %s   ,   %d  

      %s  Represents the string placeholder; (anything can be directly converted to a string, only “%s”.)

      %d It represents the digit placeholder. It can only input numbers, and the corresponding data must be int type.

   3. Data type conversion:

        int ( str )         #  String conversion to int

        str ( int )         #  int Convert into a string

   4.  ”  %%  ” To represent the “%” in a string.

         If you use a placeholder such as%s in a string, all of the% percent will become a placeholder, so you need to use “%%” to represent the “%” of the string.

         Note: if there is no use of%s and%d in the string, no need to replace it.

          eg  :  print(“My name is%s. I am 22 years old. I have learned 2%%’s Python%’Mary’.

                   print( “My name is Mary. I am 22 years old. My homework has been completed 100%.

Two basic operator

   1. Arithmetical operation, “add”, “minus”. ” Take off (module)  “.

       %  The remainder of the division is returned by a=10, b=20, and then the output of b%a is 0.

       **   The power of the second power returns to the B power of a, a=10, b=20, and then a**b is the 20 power of 10.

       //    The integer part of the return operator, a=10, b=20, 9, / 2 output result 4, 9 9 / / 2 output result 4.

   2.  Comparison operation

      ==     It is equal to the number of objects.

      !=      It is not equal to two.

      <>     It is not equal to two.

       >      greater than

       <      All operators return 1, which is true ==> True, return 0 indicates false ==> False);

      >=      More than equal or equal to

      <=      Less than equal to or equal to

   3.   A = 10, B =20)

         =     The simple assignment operator c=a+b a+b indicates that the result of the operation of C is assigned to C.

        +=    The addition assignment operator c+=a is equivalent to c=c+a.

        -=     The subtractive assignment operator c-=a is equivalent to c=c-a.

        *=     The multiplicative assignment operator c*=a is equivalent to c=c*a.

        /=      The division assignment operator c /=a is equivalent to the c=c / A;

      %=      The assignment assignment operator c a a is equivalent to c=c% a;

      **=      The power assignment operator c, a = c=c, is equivalent to * c=c * * a;

       //=      The divide and conquer assignment operator c //=a is equivalent to c=c//a.

   4.   Logic operation

       and      Boolean a byFalse,  a and bReturnFalse,Otherwise it returns” b “The value of the calculation;

         or       “Boolean”a byTrue,  a or bReturn to True, otherwise it returns ” b “The value of the calculation;

        not      Booleana byTrue,  not a ReturnFalse,Ifa byFlase,It returns to True.

        Pay attention to

                 1.   Without (), the not priority is higher than and, and and priority is higher than or.

                    That is: the priority relation is () > not >  and >or . The same priority is calculated from the left to the right.

                 2.   x or y , x For true, the value is true, X is false, the value is y;

                       x and y,x To be true, the value is y, X is false, and the value is x;

                 3.    not        The truth is not true, but it is not true.

Three coding problems

   1.   interpreter

       Python2The interpreter uses the “ASCII” to encode the content.

       Python3The interpreter uses the “UTF-8” to encode the content.

    2.  Development of coding system

         ASCII  ( American standard information exchange code 8 bit      1 byte     The expansion of use is limited;

         GBK    ( GBKCompatible ASCII)  16 bit      2 byte     Only China

            eg  :    The letter A:0100 0001 is ASCII

                       Alphabet A:0000 000001000001 GBK

      Unicode  ( Wan Guoma)   32 bit      4 byte      Waste

        UTF-8    (Variable length)    8 bit      1 byte

                                                   Chinese 24 bit      3 byte   

    3.  Unit conversion

           8 bit  =  1 byte

         1024 byte  =  1KB

         1024 KB   =   1MB

         1024 MB   =   1GB

         1024 GB   =   1TB

         1024 TB   =   1PB

 

                   ……

 

 

         

           

        

 

       

 

 

                                

 

 

 

     

 

 

 

 

        

     

 

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