C++ 关于数值极限

关于数值极限

#include <limits>
#include <iostream>

int main()
{
    std::cout << "type\t\t\tlowest()\t\tmin()\t\t\tmax()\n\n";

    std::cout << "short\t\t\t"
              << std::numeric_limits<short>::lowest() << "\t\t\t"
              << std::numeric_limits<short>::min() << "\t\t\t"
              << std::numeric_limits<short>::max() << "\n";
    std::cout << "int\t\t\t"
              << std::numeric_limits<int>::lowest() << "\t\t"
              << std::numeric_limits<int>::min() << "\t\t"
              << std::numeric_limits<int>::max() << "\n";
    std::cout << "long\t\t\t"
              << std::numeric_limits<long>::lowest() << "\t\t"
              << std::numeric_limits<long>::min() << "\t\t"
              << std::numeric_limits<long>::max() << "\n";
    std::cout << "long long\t\t"
              << std::numeric_limits<long long>::lowest() << "\t"
              << std::numeric_limits<long long>::min() << "\t"
              << std::numeric_limits<long long>::max() << "\n";
    std::cout << "unsigned short\t\t"
              << std::numeric_limits<unsigned short>::lowest() << "\t\t\t"
              << std::numeric_limits<unsigned short>::min() << "\t\t\t"
              << std::numeric_limits<unsigned short>::max() << "\n";
    std::cout << "unsigned int\t\t"
              << std::numeric_limits<unsigned int>::lowest() << "\t\t\t"
              << std::numeric_limits<unsigned int>::min() << "\t\t\t"
              << std::numeric_limits<unsigned int>::max() << "\n";
    std::cout << "unsigned long\t\t"
              << std::numeric_limits<unsigned long>::lowest() << "\t\t\t"
              << std::numeric_limits<unsigned long>::min() << "\t\t\t"
              << std::numeric_limits<unsigned long>::max() << "\n";
    std::cout << "unsigned long long\t"
              << std::numeric_limits<unsigned long long>::lowest() << "\t\t\t"
              << std::numeric_limits<unsigned long long>::min() << "\t\t\t"
              << std::numeric_limits<unsigned long long>::max() << "\n";


    system("pause");
}

64 位

在64位系统上Visual Studio 输出结果：

换为2的幂级数表示为（64位系统下）：

type	lowest()	min()	max()
short	-32768	-32768	32767
int	-2147483648	-2147483648	2147483647
long	-2147483648	-2147483648	2147483647
long long	-9223372036854775808	-9223372036854775808	9223372036854775807
unsigned short	0	0	65535
unsigned int	0	0	4294967295
unsigned long	0	0	4294967295
unsigned long long	0	0	18446744073709551615

32 位

在32位系统上Visual Studio 输出结果：

type	lowest()	min()	max()
short	-32768	-32768	32767
int	-2147483648	-2147483648	2147483647
long	-2147483648	-2147483648	2147483647
long long	-9223372036854775808	-9223372036854775808	9223372036854775807
unsigned short	0	0	65535
unsigned int	0	0	4294967295
unsigned long	0	0	4294967295
unsigned long long	0	0	18446744073709551615