10-Data type conversion

10-Data type conversion

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1: Why data type conversion is needed

• Splice data of different data types together.

Two: str()

• Function: Convert other data types to strings (str).

• str( ) The converted data is only temporarily converted and will not be permanently converted. int( ), float( )< a i=3>Similarly.

• Demo:

  s1 = 'nb'
  n1 = 1234
  f1 = 3.14
  b1 = True
  print(s1,type(s1),n1,type(n1),f1,type(f1),b1,type(b1))
  print(str(s1),type(str(s1)),str(n1),type(str(n1)),str(f1),type(str(f1)),str(b1),type(str(b1)))
  print(s1,type(s1),n1,type(n1),f1,type(f1),b1,type(b1))
  

  Output:

  nb <class 'str'> 1234 <class 'int'> 3.14 <class 'float'> True <class 'bool'>
  nb <class 'str'> 1234 <class 'str'> 3.14 <class 'str'> True <class 'str'>
  nb <class 'str'> 1234 <class 'int'> 3.14 <class 'float'> True <class 'bool'>
  

Three: int()

• Function: Convert other data types to integers (int)

• Also a temporary conversion

• When converting str type to int type, the string of str must be an integer string, otherwise an error will be reported.

• Demo:

  s2 = '324'
  n2 = 234
  f2 = 8.5
  b2 = False
  print(s2,type(s2),n2,type(n2),f2,type(f2),b2,type(b2))
  print(int(s2),type(int(s2)),int(n2),type(int(n2)),int(f2),type(int(f2)),int(b2),type(int(b2)))
  print(s2,type(s2),n2,type(n2),f2,type(f2),b2,type(b2))
  

  Output:

  324 <class 'str'> 234 <class 'int'> 8.5 <class 'float'> False <class 'bool'>
  324 <class 'int'> 234 <class 'int'> 8 <class 'int'> 0 <class 'int'>
  324 <class 'str'> 234 <class 'int'> 8.5 <class 'float'> False <class 'bool'>
  

Four: float()

• Function: Convert other data types to floating point types (float)

• Also a temporary conversion

• When converting a str type value, it must be a numeric string (integer/floating point number). If it is an integer, ".0" will be added at the end, and floating point numbers will be converted directly.

• When converting a Boolean value, 1.0 if True and 0.0 if False

• Demo:

  s3 = '52'
  n3 = 89
  f3 = 52.2
  b3 = False
  print(s3,type(s3),n3,type(n3),f3,type(f3),b3,type(b3))
  print(float(s3),type(float(s3)),float(n3),type(float(n3)),float(f3),type(float(f3)),float(b3),type(float(b3)))
  print(s3,type(s3),n3,type(n3),f3,type(f3),b3,type(b3))
  

  Output:

  52 <class 'str'> 89 <class 'int'> 52.2 <class 'float'> False <class 'bool'>
  52.0 <class 'float'> 89.0 <class 'float'> 52.2 <class 'float'> 0.0 <class 'float'>
  52 <class 'str'> 89 <class 'int'> 52.2 <class 'float'> False <class 'bool'>
  

expand:

1. Data of type int and type str cannot be connected using the connector "+", and data type conversion is required.

2. Note:

   1. Single line comments

      # 这是单行注释
      

   2. Multi-line comments

      '''
      多行注释
      多行注释
      '''
      

   3. Chinese encoding declaration comments

      • Add a Chinese declaration comment at the beginning of the file to specify the encoding format of the source code file.

      • Demo:

        #coding: gbk