std::numeric_limits<T>::infinity

 
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std::numeric_limits
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(C++11)
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(C++11)
numeric_limits::infinity
辅助类型
 
static T infinity() throw();
 (C++11 前)
static constexpr T infinity() noexcept;
 (C++11 起)

返回浮点类型 T 所表示的特殊值“正无穷大”。仅若 std::numeric_limits<T>::has_infinity == true 才有意义。在最常见的浮点数二进制表示 IEEE 754 中，正无穷大是所有指数位为 1 而所有尾数位为 0 的值。

返回值

 
T std::numeric_limits<T>::infinity()
/* non-specialized */ T()
bool false
char ​0​
signed char ​0​
unsigned char ​0​
wchar_t ​0​
char8_t ​0​
char16_t ​0​
char32_t ​0​
short ​0​
unsigned short ​0​
int ​0​
unsigned int ​0​
long ​0​
unsigned long ​0​
long long ​0​
unsigned long long ​0​
float HUGE_VALF
double HUGE_VAL
long double HUGE_VALL

示例

运行此代码
#include <iostream>
#include <limits>
int main()
{
    double max = std::numeric_limits<double>::max();
    double inf = std::numeric_limits<double>::infinity();
 
    if(inf > max)
        std::cout << inf << " is greater than " << max << '\n';
}

输出： 

inf is greater than 1.79769e+308

参阅

[静态]
 鉴别能表示特殊值“正无穷大”的浮点类型
(公开静态成员常量)