通过类与 union 的封装，可以实现一个能够存储任意基本数据类型的 Wrapper。
class Wrapper
{
public:
Wrapper(){}
Wrapper(int arg)
{
this->i = arg;
this->_type = TYPE::INT;
}
Wrapper(float arg)
{
this->f = arg;
this->_type = TYPE::FLOAT;
}
Wrapper(bool arg)
{
this->b = arg;
this->_type = TYPE::BOOL;
}
Wrapper(double arg)
{
this->d = arg;
this->_type = TYPE::DOUBLE;
}
int toInt()
{
if (this->_type == TYPE::INT)
{
return this->i;
}
if (this->_type == TYPE::FLOAT)
{
return (int)(this->f);
}
if (this->_type == TYPE::DOUBLE)
{
return (int)(this->d);
}
if (this->_type == TYPE::BOOL)
{
return this->b == 0 ? false : true;
}
}
float toFloat()
{
if (this->_type == TYPE::INT)
{
return (float)this->i;
}
if (this->_type == TYPE::FLOAT)
{
return (this->f);
}
if (this->_type == TYPE::DOUBLE)
{
return (float)(this->d);
}
if (this->_type == TYPE::BOOL)
{
return this->b == false ? 0.0f : 1.0f;
}
}
double toDouble()
{
if (this->_type == TYPE::INT)
{
return (double)this->i;
}
if (this->_type == TYPE::FLOAT)
{
return (double)this->f;
}
if (this->_type == TYPE::DOUBLE)
{
return this->d;
}
if (this->_type == TYPE::BOOL)
{
return this->b == false ? 0.0 : 1.0;
}
}
bool toBool()
{
if (this->_type == TYPE::INT)
{
return this->i == 0 ? false : true;;
}
if (this->_type == TYPE::FLOAT)
{
return this->f < 0.0000000001 ? false : true;;
}
if (this->_type == TYPE::DOUBLE)
{
return this->d < 0.0000000001 ? false : true;;
}
if (this->_type == TYPE::BOOL)
{
return this->b;
}
}
union
{
int i = 0;
float f;
bool b;
double d;
};
enum class TYPE
{
INT,
FLOAT,
DOUBLE,
BOOL
};
operator int() { return this->toInt(); }
operator float() { return this->toFloat(); }
operator bool() { return this->toBool(); }
operator double() { return this->toDouble(); }
private:
TYPE _type;
};