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Arithmetic operator

Operators are symbols that operate on constants or variables ; Expression means to connect constants or variables with operators, which conforms to java The formula of grammar .

  Single quotation mark + Is an arithmetic operator used for addition ; And double quotation marks + It's a connecting action, not an additive action

 

ASCII surface

ASCII surface （American Standard Code for Information Interchange）： American standard code for information exchange , It is a set of correspondence from byte to character in computer .