练习2-1 编写一个程序一确定分别由signed及unsigned限定的char，short，int及long类型变量的取值范围。采用打印标准头文件中的相应值以及直接计算两种方式实现。通过直接计算来确定浮点类型的取值范围是一项难度很大的任务。

不太了解如何打印取值范围。直接看答案。

通过打印头文件实现 <limits.h>

#include <stdio.h>
#include <limits.h>
main()
{
/* signed types */

printf("signed char min = %d
", SCHAR_MIN);
printf("signed char max = %d
", SCHAR_MAX);
printf("signed short min = %d
", SHRT_MIN);
printf("signed short max = %d
", SHRT_MAX);
printf("signed int min = %d
", INT_MIN);
printf("signed int max = %d
", INT_MAX);
printf("signed long min = %d
", LONG_MIN);
printf("signed long max = %d
", LONG_MAX);

/*unsigned types*/
printf("unsigned char max = %d
", UCHAR_MAX);
printf("unsigned short max = %d
", USHRT_MAX);
printf("unsigned int max = %d
", UINT_MAX);
printf("unsigned long max = %d
", ULONG_MAX);

return 0;
}

 直接计算打印取值范围；

#include <stdio.h>
/*determine ranges of types*/
main()
{
/* signed ranges of types*/

printf(" signed char min = %d 
", -(char)((unsigned char) ~0 >> 1));

printf(" signed char max = %d 
", (char)((unsigned char) ~0 >> 1));

printf(" signed short min = %d 
", -(short)((unsigned short) ~0 >> 1));

printf(" signed short max = %d 
", (short)((unsigned short) ~0 >> 1));

printf(" signed int min = %d 
", -(int)((unsigned int) ~0 >> 1));

printf(" signed int max = %d 
", (int)((unsigned int) ~0 >> 1));

printf(" signed long min = %d 
", -(long)((unsigned long) ~0 >> 1));

printf(" signed long max = %d 
", (long)((unsigned long) ~0 >> 1));


/*unsigned types*/

printf(" unsigned char max = %d 
",(unsigned char) ~0);

printf(" unsigned int max = %d 
",(unsigned int) ~0);

printf(" unsigned short max = %d 
",(unsigned short) ~0);

printf(" unsigned long max = %d 
",(unsigned long) ~0);


return 0;
}

输出：

signed char min = -127
signed char max = 127
signed short min = -32767
signed short max = 32767
signed int min = -2147483647
signed int max = 2147483647
signed long min = -2147483647
signed long max = 2147483647
unsigned char max = 255
unsigned int max = -1
unsigned short max = 65535
unsigned long max = -1