type_traits example

000_INDEX.md

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example1.cpp

#include <iostream>
#include <type_traits>

template <typename T>
typename std::enable_if<std::is_arithmetic<T>::value, T>::type
squared(T t, bool b)
{
	return b ? t * t : t;
}

int main()
{
	std::cout << squared(5, true) << std::endl;
}

example2.cpp

#include <type_traits>
#include <string>

using namespace std;

template <typename T, typename Enable = void>
class Attrib
{
	T* t;
public:
	T* operator->() { return t; }
};

template <typename T>
class Attrib<typename T, typename enable_if<is_arithmetic<T>::value | is_same<T, string>::value>::type>
{
	T* t;
public:
	Attrib(T& t) { this->t = &t; }
	T* operator->() { return t; }
};

/*template <typename T>
class Attrib<typename T, typename enable_if<is_same<T, string>::value>::type>
{
	T* t;
public:
	Attrib(T& t) { this->t = &t; }
	T* operator->() { return t; }
};*/

int main()
{
	int a;
	Attrib<int> A(a);

	char c;
	Attrib<char> C(c);

	string s;
	Attrib<string> S(s);
}

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