c++数据的取值范围 .

 

c++数据的取值范围

#include "stdio.h"
#include "iostream"
using namespace std;
int main()
{

char a1=-128;//-128~+127
short b1=-32768;// -32768~+32767
int c1=-2147483648;//-2147483648~+2147483647
long d1=-2147483648;//-2147483648~+2147483647
long long x1=-9223372036854775808;//-9223372036854775808~9223372036854775807
//以下取-1转化后为最大值
unsigned char a2=-1;//0~255
unsigned short b2=-1;// 0~65535
unsigned int c2=-1;//0~4294967295
unsigned long d2=-1;//0~4294967295
unsigned long long x2=-1;//0~18446744073709551615
float e=100/3.0;//10e±38,6位有效数字-7
double f=100.0/3;//10e±308,12位有效数字-16
long double g=100.0/3;//10±4932,15位有效数字-16
cout.precision(50);
cout<<"测试平台:Intel P4,XPsp3-32bit,VC8.0"<<endl;
cout<<"浮点数精度测试100除以3"<<endl;
cout<<"float /t/t e="<<e<<endl;
cout<<"double /t/t f="<<f<<endl;
cout<<"long double /t g="<<g<<endl;
cout<<"有符号数取最小值分别是"<<endl;
printf("char a1   ->%d/n",a1);
cout<<"short b1 ="<<b1<<endl;
cout<<"int c1   ="<<c1<<endl;
cout<<"long d1   ="<<d1<<endl;
cout<<"long long x1 ="<<x1<<endl;
cout<<"....最低值再减一,溢出得最大值"<<endl;
a1--;b1--;c1--;d1--;x1--;
printf("char a1   ->%d/n",a1);
cout<<"short b1 ="<<b1<<endl;
cout<<"int c1   ="<<c1<<endl;
cout<<"long d1   ="<<d1<<endl;
cout<<"long long x1 ="<<x1<<endl;
cout<<"无符号数取最大值(-1)分别是"<<endl;
printf("unsigned char a2 ->%d/n",a2);
cout<<"unsigned short b2 ="<<b2<<endl;
cout<<"unsigned int c2   ="<<c2<<endl;
cout<<"unsigned long d2 ="<<d2<<endl;
cout<<"unsigned long long x2 ="<<x2<<endl;
cout<<"...最大值,加一后,溢出,归零(最小值)"<<endl;
a2++;b2++;c2++;d2++;x2++;
printf("unsigned char a2 ->%d/n",a2);
cout<<"unsigned short b2 ="<<b2<<endl;
cout<<"unsigned int c2   ="<<c2<<endl;
cout<<"unsigned long d2 ="<<d2<<endl;
cout<<"unsigned long long x2 ="<<x2<<endl;
cout<<"....零减一后,又溢出,得最大值,所以别拿无数号数和小于0比"<<endl;
a2--;b2--;c2--;d2--;x2--;
printf("unsigned char a2 ->%d/n",a2);
cout<<"unsigned short b2 ="<<b2<<endl;
cout<<"unsigned int c2   ="<<c2<<endl;
cout<<"unsigned long d2 ="<<d2<<endl;
cout<<"unsigned long long x2 ="<<x2<<endl;

cout<<"存储大小"<<endl;
cout<<"sizeof(char)   ="<<sizeof(char)<<"字节" <<endl;
cout<<"sizeof(short)   ="<<sizeof(short) <<"字节" <<endl;
cout<<"sizeof(int)   ="<<sizeof(int)<<"字节" <<endl;
cout<<"sizeof(long)   ="<<sizeof(long )<<"字节" <<endl;
cout<<"sizeof(long long) ="<<sizeof(long long)<<"字节" <<endl<<endl;

cout<<"sizeof(unsigned char)   ="<<sizeof(unsigned char)<<"字节" <<endl;
cout<<"sizeof(unsigned short)   ="<<sizeof(unsigned short )<<"字节" <<endl;
cout<<"sizeof(unsigned int)   ="<<sizeof(unsigned int )<<"字节" <<endl;
cout<<"sizeof(unsigned long)   ="<<sizeof(unsigned long )<<"字节" <<endl;
cout<<"sizeof(unsigned long long) ="<<sizeof(unsigned long long)<<"字节" <<endl<<endl;

cout<<"sizeof(float)   ="<<sizeof(float )<<"字节" <<endl;
cout<<"sizeof(double)   ="<<sizeof(double)<<"字节" <<endl;
cout<<"sizeof(long double) ="<<sizeof(long double )<<"字节" <<endl;
//其他方法#include "limits"//其他方法
/*
      cout<<"---------以下最大值--------------------"<<endl;  
      cout<<   numeric_limits<unsigned long long >::max()   <<endl;    
      cout<<   numeric_limits< long long >::max()   <<endl;    
      cout<<"---------以下最小值--------------------"<<endl;  
      cout<<   numeric_limits<unsigned long long >::min()   <<endl;    
      cout<<   numeric_limits<long long>::min()   <<endl;    
*/
//long long 取值-2E(sizeof(long long)*8)/2   ~   2E(sizeof(long long)*8)-1
//unsigned long long 取值0~2E(sizeof(unsigned long long)*8)-1

return 0;
}

 

出处：http://hi.baidu.com/linyuanyumeng/blog/item/bc02bf2bfc66b1f6e6cd40e3.html