std::numeric_limits<T>::has_infinity
来自 cppreference.cn
static const bool has_infinity; |
(C++11 前) | |
static constexpr bool has_infinity; |
(C++11 起) | |
std::numeric_limits<T>::has_infinity 的值为 true ,对于所有能够将正无穷表示为独特特殊值的类型 T
。此常量对所有浮点类型都有意义,并且如果 std::numeric_limits<T>::is_iec559 == true,则保证为 true。
[编辑] 标准特化
T
|
std::numeric_limits<T>::has_infinity 的值 |
/* 未特化 */ | false |
bool | false |
char | false |
signed char | false |
unsigned char | false |
wchar_t | false |
char8_t (C++20起) | false |
char16_t (C++11起) | false |
char32_t (C++11起) | false |
short | false |
unsigned short | false |
int | false |
unsigned int | false |
long | false |
unsigned long | false |
long long (C++11起) | false |
unsigned long long (C++11起) | false |
float | 通常为 true |
double | 通常为 true |
long double | 通常为 true |
[编辑] 示例
运行此代码
#include <iostream> #include <limits> int main() { std::cout << std::boolalpha << std::numeric_limits<int>::has_infinity << '\n' << std::numeric_limits<long>::has_infinity << '\n' << std::numeric_limits<float>::has_infinity << '\n' << std::numeric_limits<double>::has_infinity << '\n'; }
可能的输出
false false true true
[编辑] 另请参阅
[静态] |
返回给定浮点类型的正无穷大值 (public static member function) |
[静态] |
确定可以表示特殊值“安静的非数”(quiet not-a-number,NaN)的浮点类型 (public static member constant) |
确定可以表示特殊值“发信的非数”(signaling not-a-number,NaN)的浮点类型 (public static member constant) |