I've done an example of 'template specialization'. Here is the code:
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// template specialization
#include <iostream>
using namespace std;
// class template:
template <class T>
class mycontainer {
private:
T element;
public:
// only prototype
mycontainer (T);
T increase ();
};
// class method definition
template <class T>
mycontainer<T> :: mycontainer(T arg) {
element = arg;
}
template <class T>
T mycontainer<T> :: increase () {
return ++element;
}
// class template specialization:
template <>
class mycontainer <char> { // specialized for char type
private:
char element;
public:
mycontainer(char arg) {
element = arg;
}
char uppercase() {
if ((element >= 'a') && (element <= 'z')) {
element += 'A'-'a';
return element;
}
return '0';
}
};
//
int main () {
mycontainer<int> myint (7);
mycontainer<char> mychar ('j');
//
cout << myint.increase() << endl;
cout << mychar.uppercase() << endl;
//
return 0;
}
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The compiler compiled this code successfully, but when I try to move the definition of the constructor and the method outside the class, the compiler cannot compile it.
Here is the code with outside-class-definition:
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// template specialization
#include <iostream>
using namespace std;
// class template:
template <class T>
class mycontainer {
private:
T element;
public:
// only prototype
mycontainer (T);
T increase ();
};
// class method definition
template <class T>
mycontainer<T> :: mycontainer(T arg) {
element = arg;
}
template <class T>
T mycontainer<T> :: increase () {
return ++element;
}
// class template specialization:
template <>
class mycontainer <char> { // specialized for char type
private:
char element;
public:
// only prototype
mycontainer(char);
char uppercase();
};
// definition
template <>
mycontainer<char> :: mycontainer(char arg) {
element = arg;
}
template <>
char mycontainer<char> :: uppercase () {
if ((element >= 'a') && (element <= 'z')) {
element += 'A'-'a';
return element;
}
return '0';
}
//
int main () {
mycontainer<int> myint (7);
mycontainer<char> mychar ('j');
//
cout << myint.increase() << endl;
cout << mychar.uppercase() << endl;
//
return 0;
}
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The compiler generated these errors:
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... error C2910: 'mycontainer<char>::{ctor}' : cannot be explicitly specialized
... error C2910: 'mycontainer<char>::uppercase' : cannot be explicitly specialized
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Even when I add the 'char' between the angle, the compiler still gave errors.
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template <char>
mycontainer<char> :: mycontainer(char arg) {
element = arg;
}
template <char>
char mycontainer<char> :: uppercase () {
if ((element >= 'a') && (element <= 'z')) {
element += 'A'-'a';
return element;
}
return '0';
}
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With this code, The compiler generated these errors:
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... error C2244: 'mycontainer<char>::{ctor}' : unable to match function definition to an existing declaration
definition
'mycontainer<char>::mycontainer(char)'
existing declarations
'mycontainer<char>::mycontainer(const mycontainer<char> &)'
'mycontainer<char>::mycontainer(char)'
... error C2244: 'mycontainer<char>::uppercase' : unable to match function definition to an existing declaration
TemplateSpecialization3.cpp(36) : see declaration of mycontainer<char>::uppercase'
definition
'char mycontainer<char>::uppercase(void)'
existing declarations
'char mycontainer<char>::uppercase(void)'
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I use the compiler "
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 15.00.21022.08 for 80x86", and compile the source-code with "cl /clr *.cpp" command.
Did anyone encounter this problem? Why? Is my second code incorrect or the compiler doesn't allow?
Thank you very much :)
