c++数据类型（整型/浮点型/字符串/数组/引用/结构体（内存对齐）/类（虚函数））定义、所占字节数、最大最小值

所占字节数与OS、编译器、机器有关。同样是32位操作系统，vc++编译器中int占4个字节，turboc中则是2个字节。

本文在以下环境中实验：

OS	CentOS release 5.4
g++	x86_64-redhat-linux-g++

一、整型/浮点型/字符串/数组/引用：

#include<iostream>
#include<string>
#include<limits>
using namespace std;

int main()
{
    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 << "   " << 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 << "   " << 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 << "long long: \t" << "所占字节数：" << sizeof(long long);
    cout << "\t最大值：" << (numeric_limits<long long>::max)();
    cout << "\t最小值：" << (numeric_limits<long 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: \tt" << "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 << "ssize_t: \t" << "所占字节数：" << sizeof(ssize_t);
    cout << "\t最大值：" << (numeric_limits<ssize_t>::max)();
    cout << "\t最小值：" << (numeric_limits<ssize_t>::min)() << endl;
    cout << "string: \t" << "所占字节数：" << sizeof(string) << endl;
    cout << "string:hello,world\t" << "所占字节数：" << sizeof("hello,world") << endl;
    char a[20];
    cout << "char a[20] \t" << "所占字节数：" << sizeof(a) << endl;
    int a1;
    int &ra=a1;
    cout << "int &ra \t" << "所占字节数：" << sizeof(ra) << endl;
    cout << "type: \t\t" << "************size**************"<< endl;
    return 0;
}

实验结果：

一个字节做为定义为byte=8bit，无符号数据

1）定义说明：

整型定义：包含整数、布尔、字符三种算数类型。

wchar定义：它是c/c++字符类型，只一种扩展的存储方式。因为char只有8位，最多能表示256个字符，但是许多外文字符集所包含的数目超过256个，char型无法表示。

size_t定义：一个基本的无符号整数的C / C + +类型， 它是sizeof操作符返回的结果类型 。

查找步骤1./usr/include/linux/types.h