【C/C++】基本数据类型

标准C基本数据类型：int char long short float double void以及它们与signed、unsigned的组合。标准C++增加了bool型和wchar_t型，在32位操作系统上，它们的长度如下表：

类型标识符	类型说明	长度（字节）	范围	备注
char	字符型	1	-128 ~ 127	-27 ~ (27 -1)
unsigned char	无符字符型	1	0 ~ 255	0 ~ (28 -1)
short int	短整型	2	-32768 ~ 32767	2-15 ~ (215 - 1)
unsigned short int	无符短整型	2	0 ~ 65535	0 ~ (216 - 1)
long int	长整型	4	-2147483648 ~ 2147483646	-231 ~ (231 - 0)
int	整型	4	-2147483648 ~ 2147483647	-231 ~ (231 - 1)
unsigned int	无符整型	4	0 ~ 4294967295	0 ~ (232-1)
float	实型（单精度）	4	1.1810-38 ~ 3.401038	7位有效位
double	实型（双精度）	8	2.2310-308 ~ 1.7910308	15位有效位
long double	实型（长双精度）	10	3.3710-4932 ~ 1.18104932	19位有效位

在不同的平台下，字长不同，具体可以通过以下代码查看：

#include<stdio.h>  
  
void main()  
{  
    //字符型 有符号和无符号的字节数一样 只是范围不同  
    printf("char is %d\n",sizeof(char));  
    printf("unsigned char is %d\n",sizeof(unsigned char));  
  
    //整数型  
    printf("short int is %d\n",sizeof(short int));  
    printf("unsigned short int is %d\n",sizeof(unsigned short int));  
    printf("long int is %d\n",sizeof(long int));  
    printf("int is %d\n",sizeof(int));  
    printf("unsigned int is %d\n",sizeof(unsigned int));  
      
    //浮点型  
    printf("float is %d\n",sizeof(float));  
    printf("double is %d\n",sizeof(double));  
    printf("long double is %d\n",sizeof(long double));  
      
}

在头文件climits.h中，定义了符号常量来表示类型的限制。其列表如下：

name	expresses	value*
CHAR_BIT	Number of bits in a char object (byte)	8 or greater
SCHAR_MIN	Minimum value for an object of type signed char	-127 (-27+1) or less
SCHAR_MAX	Maximum value for an object of type signed char	127 (27-1) or greater
UCHAR_MAX	Maximum value for an object of type unsigned char	255 (28-1) or greater
CHAR_MIN	Minimum value for an object of type char	either SCHAR_MIN or 0
CHAR_MAX	Maximum value for an object of type char	either SCHAR_MAX or UCHAR_MAX
MB_LEN_MAX	Maximum number of bytes in a multibyte character, for any locale	1 or greater
SHRT_MIN	Minimum value for an object of type short int	-32767 (-215+1) or less
SHRT_MAX	Maximum value for an object of type short int	32767 (215-1) or greater
USHRT_MAX	Maximum value for an object of type unsigned short int	65535 (216-1) or greater
INT_MIN	Minimum value for an object of type int	-32767 (-215+1) or less
INT_MAX	Maximum value for an object of type int	32767 (215-1) or greater
UINT_MAX	Maximum value for an object of type unsigned int	65535 (216-1) or greater
LONG_MIN	Minimum value for an object of type long int	-2147483647 (-231+1) or less
LONG_MAX	Maximum value for an object of type long int	2147483647 (231-1) or greater
ULONG_MAX	Maximum value for an object of type unsigned long int	4294967295 (232-1) or greater
LLONG_MIN	Minimum value for an object of type long long int	-9223372036854775807 (-263+1) or less
LLONG_MAX	Maximum value for an object of type long long int	9223372036854775807 (263-1) or greater
ULLONG_MAX	Maximum value for an object of type unsigned long long int	18446744073709551615 (264-1) or greater

* 其精确值依赖于你的系统和库的实现