C/C++各种类型int、long、double表示范围(最大最小值)

 

在vs 2013 中代码如下:

// ConsoleApplication2.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<iostream>  
#include<string>  
#include <limits>  
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
	cout << "type: \t\t" << "************size**************" << endl;
	cout << "bool: \t\t" << "所占字节数:" << sizeof(bool);
	cout << "\t最大值:" << (numeric_limits<bool>::max)();
	cout << "\t\t最小值:" << (numeric_limits<bool>::min)() << endl;
	cout << "char: \t\t" << "所占字节数:" << sizeof(char);
	cout << "\t最大值:" << (numeric_limits<char>::max)();
	cout << "\t\t最小值:" << (numeric_limits<char>::min)() << endl;
	cout << "signed char: \t" << "所占字节数:" << sizeof(signed char);
	cout << "\t最大值:" << (numeric_limits<signed char>::max)();
	cout << "\t\t最小值:" << (numeric_limits<signed char>::min)() << endl;
	cout << "unsigned char: \t" << "所占字节数:" << sizeof(unsigned char);
	cout << "\t最大值:" << (numeric_limits<unsigned char>::max)();
	cout << "\t\t最小值:" << (numeric_limits<unsigned char>::min)() << endl;
	cout << "wchar_t: \t" << "所占字节数:" << sizeof(wchar_t);
	cout << "\t最大值:" << (numeric_limits<wchar_t>::max)();
	cout << "\t\t最小值:" << (numeric_limits<wchar_t>::min)() << endl;
	cout << "short: \t\t" << "所占字节数:" << sizeof(short);
	cout << "\t最大值:" << (numeric_limits<short>::max)();
	cout << "\t\t最小值:" << (numeric_limits<short>::min)() << endl;
	cout << "int: \t\t" << "所占字节数:" << sizeof(int);
	cout << "\t最大值:" << (numeric_limits<int>::max)();
	cout << "\t最小值:" << (numeric_limits<int>::min)() << endl;
	cout << "unsigned: \t" << "所占字节数:" << sizeof(unsigned);
	cout << "\t最大值:" << (numeric_limits<unsigned>::max)();
	cout << "\t最小值:" << (numeric_limits<unsigned>::min)() << endl;
	cout << "long: \t\t" << "所占字节数:" << sizeof(long);
	cout << "\t最大值:" << (numeric_limits<long>::max)();
	cout << "\t最小值:" << (numeric_limits<long>::min)() << endl;
	cout << "unsigned long: \t" << "所占字节数:" << sizeof(unsigned long);
	cout << "\t最大值:" << (numeric_limits<unsigned long>::max)();
	cout << "\t最小值:" << (numeric_limits<unsigned long>::min)() << endl;
	cout << "double: \t" << "所占字节数:" << sizeof(double);
	cout << "\t最大值:" << (numeric_limits<double>::max)();
	cout << "\t最小值:" << (numeric_limits<double>::min)() << endl;
	cout << "long double: \t" << "所占字节数:" << sizeof(long double);
	cout << "\t最大值:" << (numeric_limits<long double>::max)();
	cout << "\t最小值:" << (numeric_limits<long double>::min)() << endl;
	cout << "float: \t\t" << "所占字节数:" << sizeof(float);
	cout << "\t最大值:" << (numeric_limits<float>::max)();
	cout << "\t最小值:" << (numeric_limits<float>::min)() << endl;
	cout << "size_t: \t" << "所占字节数:" << sizeof(size_t);
	cout << "\t最大值:" << (numeric_limits<size_t>::max)();
	cout << "\t最小值:" << (numeric_limits<size_t>::min)() << endl;
	cout << "string: \t" << "所占字节数:" << sizeof(string) << endl;
	// << "\t最大值:" << (numeric_limits<string>::max)() << "\t最小值:" << (numeric_limits<string>::min)() << endl;  
	cout << "type: \t\t" << "************size**************" << endl;
	fflush(stdin);
	getchar();
	return 0;
}

效果图如下:

TM截图20140929090633

 

/*运行结果分析:

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。

 

代码转自互联网http://blog.csdn.net/xuexiacm/article/details/8122267

二〇一四年九月二十九日 09:07:37

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