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C/C++中各种类型int、long、double、char表示范围(最大最小值)(转)

时间:2016-02-20 22:58:27      阅读:478      评论:0      收藏:0      [点我收藏+]

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 1 #include<iostream>
 2 #include<string>
 3 #include <limits>
 4 using namespace std;
 5 
 6 int main()
 7 {
 8     cout << "type: \t\t" << "************size**************"<< endl;
 9     cout << "bool: \t\t" << "所占字节数:" << sizeof(bool);
10     cout << "\t最大值:" << (numeric_limits<bool>::max)();
11     cout << "\t\t最小值:" << (numeric_limits<bool>::min)() << endl;
12     cout << "char: \t\t" << "所占字节数:" << sizeof(char);
13     cout << "\t最大值:" << (numeric_limits<char>::max)();
14     cout << "\t\t最小值:" << (numeric_limits<char>::min)() << endl;
15     cout << "signed char: \t" << "所占字节数:" << sizeof(signed char);
16     cout << "\t最大值:" << (numeric_limits<signed char>::max)();
17     cout << "\t\t最小值:" << (numeric_limits<signed char>::min)() << endl;
18     cout << "unsigned char: \t" << "所占字节数:" << sizeof(unsigned char);
19     cout << "\t最大值:" << (numeric_limits<unsigned char>::max)();
20     cout << "\t\t最小值:" << (numeric_limits<unsigned char>::min)() << endl;
21     cout << "wchar_t: \t" << "所占字节数:" << sizeof(wchar_t);
22     cout << "\t最大值:" << (numeric_limits<wchar_t>::max)();
23     cout << "\t\t最小值:" << (numeric_limits<wchar_t>::min)() << endl;
24     cout << "short: \t\t" << "所占字节数:" << sizeof(short);
25     cout << "\t最大值:" << (numeric_limits<short>::max)();
26     cout << "\t\t最小值:" << (numeric_limits<short>::min)() << endl;
27     cout << "int: \t\t" << "所占字节数:" << sizeof(int);
28     cout << "\t最大值:" << (numeric_limits<int>::max)();
29     cout << "\t最小值:" << (numeric_limits<int>::min)() << endl;
30     cout << "unsigned: \t" << "所占字节数:" << sizeof(unsigned);
31     cout << "\t最大值:" << (numeric_limits<unsigned>::max)();
32     cout << "\t最小值:" << (numeric_limits<unsigned>::min)() << endl;
33     cout << "long: \t\t" << "所占字节数:" << sizeof(long);
34     cout << "\t最大值:" << (numeric_limits<long>::max)();
35     cout << "\t最小值:" << (numeric_limits<long>::min)() << endl;
36     cout << "unsigned long: \t" << "所占字节数:" << sizeof(unsigned long);
37     cout << "\t最大值:" << (numeric_limits<unsigned long>::max)();
38     cout << "\t最小值:" << (numeric_limits<unsigned long>::min)() << endl;
39     cout << "double: \t" << "所占字节数:" << sizeof(double);
40     cout << "\t最大值:" << (numeric_limits<double>::max)();
41     cout << "\t最小值:" << (numeric_limits<double>::min)() << endl;
42     cout << "long double: \t" << "所占字节数:" << sizeof(long double);
43     cout << "\t最大值:" << (numeric_limits<long double>::max)();
44     cout << "\t最小值:" << (numeric_limits<long double>::min)() << endl;
45     cout << "float: \t\t" << "所占字节数:" << sizeof(float);
46     cout << "\t最大值:" << (numeric_limits<float>::max)();
47     cout << "\t最小值:" << (numeric_limits<float>::min)() << endl;
48     cout << "size_t: \t" << "所占字节数:" << sizeof(size_t);
49     cout << "\t最大值:" << (numeric_limits<size_t>::max)();
50     cout << "\t最小值:" << (numeric_limits<size_t>::min)() << endl;
51     cout << "string: \t" << "所占字节数:" << sizeof(string) << endl;
52     // << "\t最大值:" << (numeric_limits<string>::max)() << "\t最小值:" << (numeric_limits<string>::min)() << endl;
53     cout << "type: \t\t" << "************size**************"<< endl;
54     return 0;
55 }

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以上结果已经很明白了,一下补充说明几点:

概念、整型:表示整数、字符和布尔值的算术类型合称为整型(integral type)。

关于带符号与无符号类型:整型 int、stort  和  long 都默认为带符号型。要获得无符号型则必须制定该类型为unsigned,比如unsigned long。unsigned int类型可以简写为unsigned,也就是说,unsigned后不加其他类型说明符就意味着是unsigned int。

一字节表示八位,即:1byte = 8 bit;

int: 4byte =  32 bit 有符号signed范围:2^31-1 ~ -2^31即:2147483647 ~ -2147483648无符号unsigned范围:2^32-1 ~ 0即:4294967295 ~ 0

long: 4 byte = 32 bit 同int型

double: 8 byte = 64 bit 范围:1.79769e+308 ~ 2.22507e-308

long double: 12 byte = 96 bit 范围: 1.18973e+4932 ~ 3.3621e-4932

float: 4 byte = 32 bit 范围: 3.40282e+038 ~ 1.17549e-038

int、unsigned、long、unsigned long 、double的数量级最大都只能表示为10亿,即它们表示十进制的位数不超过10个,即可以保存所有9位整数。而short只是能表示5位;

 

另外对于浮点说而言:使用double类型基本上不会有错。在float类型中隐式的精度损失是不能忽视的,二双精度计算的代价相对于单精度可以忽略。事实上,在有些机器上,double类型比float类型的计算要快得多。float型只能保证6位有效数字,而double型至少可以保证15位有效数字(小数点后的数位),long double型提供的精度通常没有必要,而且还要承担额外的运行代价。

double是8字节共64位,其中小数位占52位,2-^52=2.2204460492503130808472633361816e-16,量级为10^-16,故能够保证2^-15的所有精度。

在有些机器上,用long类型进行计算所付出的运行时代价远远高于用int类型进行同样计算的代价,所以算则类型前要先了解程序的细节并且比较long类型与int类型的实际运行时性能代价。

转自:http://blog.csdn.net/xuexiacm/article/details/8122267

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C/C++中各种类型int、long、double、char表示范围(最大最小值)(转)

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原文地址:http://www.cnblogs.com/yoyo-sincerely/p/5204053.html

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