问题描述
我使用C ++(不是11)和使用一些库具有不同的typedefs整数数据类型。有什么办法,我可以断言两个typedef是相同的类型?我自己想出了以下解决方案..它是安全吗?
感谢
I am using C++ (not 11) and using some libraries which have different typedefs for integer data types. Is there any way I can assert that two typedefs are the same type? I've come up with the following solution myself.. is it safe?Thanks
template<typename T>
struct TypeTest
{
static void Compare(const TypeTest& other) {}
};
typedef unsigned long long UINT64;
typedef unsigned long long UINT_64;
typedef unsigned int UINT_32;
int main()
{
TypeTest<UINT64>::Compare(TypeTest<UINT64>()); // pass
TypeTest<UINT64>::Compare(TypeTest<UINT_64>()); // pass
TypeTest<UINT64>::Compare(TypeTest<UINT_32>()); // fail
}
推荐答案
+11,您可以使用 std :: is_same< T,U> :: value
。
In C++11, you could use std::is_same<T,U>::value
.
没有C ++ 11,你可以自己实现这个功能:
Since you don't have C++11, you could implement this functionality yourself as:
template<typename T, typename U>
struct is_same
{
static const bool value = false;
};
template<typename T>
struct is_same<T,T> //specialization
{
static const bool value = true;
};
完成!
static_assert
as:
template<bool> struct static_assert;
template<> struct static_assert<true> {}; //specialization
现在您可以使用它们:
static_assert<is_same<UINT64,UINT64>::value>(); //pass
static_assert<is_same<UINT64,UINT32>::value>(); //fail
或者您可以将此包装在宏中:
Or you could wrap this in a macro as:
#define STATIC_ASSERT(x) { static_assert<x> static_assert_failed; (void) static_assert_failed; }
然后使用:
STATIC_ASSERT(is_same<UINT64,UINT64>::value); //pass
STATIC_ASSERT(is_same<UINT64,UINT32>::value); //pass
如果使用宏,则会在编译器生成的消息中看到以下字符串if断言失败:
If you use macro, then you would see the following string in the compiler generated message if the assert fails:
static_assert_failed
这是有帮助的。使用错误消息中的其他信息,您将能够找出它失败的原因。
which is helpful. With the other information in the error message, you would be able to figure out why it failed.
希望有帮助。
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