c++基本数据类型的大小及范围

1 数据大小

注意，c语言中没有bool类型，用0代表false，用非0代表true

测试平台：VS2015的debug模式下X86

#include 
using namespace std;

int main(int argc, char* argv[]) {
	cout << "sizeof(bool) = " << sizeof(bool) << endl;
	cout << "sizeof(char) = " << sizeof(char) << endl;
	cout << "sizeof(unsigned char) = " << sizeof(unsigned char) << endl;
	cout << "sizeof(short int) = " << sizeof(short int) << endl;
	cout << "sizeof(int) = " << sizeof(int) << endl;
	cout << "sizeof(unsigned int) = " << sizeof(unsigned int) << endl;
	cout << "sizeof(float) = " << sizeof(float) << endl;
	cout << "sizeof(long) = " << sizeof(long) << endl;
	cout << "sizeof(unsigned long) = " << sizeof(unsigned long) << endl;
	cout << "sizeof(double) = " << sizeof(double) << endl;
	cout << "sizeof(long long) = " << sizeof(long long) << endl;

	cout << "指针" << endl;

	cout << "sizeof(bool*) = " << sizeof(bool*) << endl;
	cout << "sizeof(char*) = " << sizeof(char*) << endl;
	cout << "sizeof(unsigned char*) = " << sizeof(unsigned char*) << endl;
	cout << "sizeof(short int*) = " << sizeof(short int*) << endl;
	cout << "sizeof(int*) = " << sizeof(int*) << endl;
	cout << "sizeof(unsigned int*) = " << sizeof(unsigned int*) << endl;
	cout << "sizeof(float*) = " << sizeof(float*) << endl;
	cout << "sizeof(long*) = " << sizeof(long*) << endl;
	cout << "sizeof(unsigned long*) = " << sizeof(unsigned long*) << endl;
	cout << "sizeof(double*) = " << sizeof(double*) << endl;
	cout << "sizeof(long long*) = " << sizeof(long*) << endl;

	system("pause");
	return 0;
}

运行如下：

总结如下：

数据类型	32位
bool	1
char	1
unsigned char	1
short int	2
int	4
指针	4
unsigned int	4
float	4
long	4
unsigned long	4
double	8
long long	8
指针	4

测试平台：VS2015的debug模式下X64

代码同上

总结

数据类型	64位
bool	1
char	1
unsigned char	1
short int	2
int	4
指针	8
unsigned int	4
float	4
long	4
unsigned long	4
double	8
long long	8

这里有个怪异的地方 ，我们平常说long是8个字节，这里却是4个字节。

我决定试试linux平台，看看结果。

先看32位

在g++后面添加-m32

g++ -m32 -自己的代码

需要安装一些库

sudo apt-get install build-essential module-assistant  
sudo apt-get install gcc-multilib g++-multilib  

结果

 与windows下32位一样

再测64位

 发现这里long和unsigned long都是8个字节，其他没有变化。

 总结

数据类型	32位	64位(windows)	64位(linux)
bool	1	1	1
char	1	1	1
unsigned char	1	1	1
short int	2	2	2
int	4	4	4
指针	4	8	8
unsigned int	4	4	4
float	4	4	4
long	4	4	8
unsigned long	4	4	8
double	8	8	8
long long	8	8	8

windows系统和linux系统下，大部分数据类型的大小都一样，只有long和unsigned long不一样；

在window下64位机器上，long和unsigned long都是4个字节

在linux下64位机器人上，long和unsigned long都是8个字节

2 范围

数据类型	占内存字节数	表示范围	数量级
char（signed char）	1	-128~127	2
unsigned char	1	0~255	2
short int（signed short int）	2	-32,768~32,767	4
unsigned short int	2	0~65,535	4
int（signed int）	4	-2,147,483,648~2,147,483,647（-231 ~ 231-1）	9
unsigned int	4	0~4,294,967,295	9
long int（signed long int）	4	-2,147,483,648~2,147,483,647（-231 ~ 231-1）	9
unsigned long int	4	0~4,294,967,295	9
float	4	-3.4x10-38 ~ 3.4x1038	38
double	8	-1.7x10-308 ~ 1.7x10308	308
long double	8	-1.7x10-308 ~ 1.7x10308	308

参考：

1、ubuntu G++编译32位_houxy12的博客-CSDN博客_g++ 编译32位

2、(1条消息) c语言基本数据类型大小（32位/64位操作系统）_华科⁢⁢⁡⁢的博客-CSDN博客_c语言变量类型64位