Basic

• effect： String value, generally used for assignment or judgment

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• effect： Used to concatenate strings

• parameter： The number of parameters can be any number, the parameters can also be any type, but they will all be converted to string

• example：
  
  computational results:

      0.14
  

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• effect： Concatenated string

• parameter： the parameters can be any type, but they will all be converted to string

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• effect： Returns the length of the string, the return value of int type

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• effect： Check whether there is a corresponding character in the character, and return the position, if not, return 0
  You can set to return the position of the first character found, or return the position of the last character

• parameter： Both parameters are of string type, the first parameter is the main string, and the second parameter represents the character to be found in the first parameter

• example：
  
  computational results:

      1
      7
  

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• effect： Get the string at the specified position in the text

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• effect： Get the characters between the specified subscripts in the text

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• effect： don’t say so much

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• effect： Needless to say

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