Use the template to determine the type of a variable during compilation

Using templates can accomplish a lot of seemingly incredible things, such as the following, you can achieve static type judgment during compilation.

 

# Include <string>
# Include <iostream>
 
Template <typename T>
Class TypeChecker;
 
Template <> class TypeChecker <std: string>
{
Public:
 
Static const int TYPE = 1;
};
 
Template <> class TypeChecker <const char *>
{
Public:
 
Static const int TYPE = 2;
};
 
Template <> class TypeChecker <char *>
{
Public:
 
Static const int TYPE = 3;
};
 
Int main ()
{
Std: string dummy = "";
If (TypeChecker <typeof (dummy) >:: TYPE = 1)
{
Std: cout <"std: string" <std: endl;
}
 
Char * data = "";
If (! TypeChecker <typeof (data) >:: TYPE = 2)
{
Std: cout <"const char *" <std: endl;
}
 
}

From this we can see that the template basically defines all the situations you need, and then let the compiler choose which one applies.

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