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Explains how to generate constant literal descriptors.

Generate a constant literal as follows:

      
       
      
      _LIT(name, string);
     

where name is a C++ variable name and string is the literal text enclosed in a pair of double quotes.

All the code fragments use the build independent form but they are equally valid if replaced by the explicit 16 bit variant or the explicit 8 bit variant.

As name represents a constant variable, it is conventional for the variable name to start with a capital K , for example:

      
       
      
      _LIT(KTxtMatchString,"Hello");
     

This generates the constant literal descriptor:

      
       
      
      const static TLitC<5> KTxtMatchString;
     

and this is initialised to contain the string Hello . Developers never need to code a TLitC class explicitly; it is always be constructed through the macro.

This constant literal descriptor can be passed directly to functions which are prototyped to take a const TDesC& type:

      
       
      
      TBufC<32> x;
...
x.Match(KTxtMatchString);
...
     

The literal descriptor classes: TLitC16 , TLitC8 , TLitC16 , also provide a conversion operator so that they can be passed to functions which take a const TRefByValue<const TDesC> type. This means that they can be passed to functions such as TDes::Format() :

      
       
      
      _LIT(KFormat1,"Length is %d");
...
TBuf<256> x;
...
x.Format(KFormat1,8);
...
     

The & and the () operators acting on a constant literal return a const TDesC* and a const TDesC& type respectively:

      
       
      
      ...
_LIT(KTxtMatchString,"Hello");
_LIT(KFormat2,"Text is %S");
...
     

      
       
      
      TInt length;
length = KTxtMatchString().Length();
...
TBuf<256> x;
x.Format(KFormat2,&KTxtMatchString);
...