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>
1 #include <stdio.h> 2 #include <limits.h> 3 main() 4 { 5 /* signed types */ 6 7 printf("signed char min = %d\n", SCHAR_MIN); 8 printf("signed char max = %d\n", SCHAR_MAX); 9 printf("signed short min = %d\n", SHRT_MIN); 10 printf("signed short max = %d\n", SHRT_MAX); 11 printf("signed int min = %d\n", INT_MIN); 12 printf("signed int max = %d\n", INT_MAX); 13 printf("signed long min = %d\n", LONG_MIN); 14 printf("signed long max = %d\n", LONG_MAX); 15 16 /*unsigned types*/ 17 printf("unsigned char max = %d\n", UCHAR_MAX); 18 printf("unsigned short max = %d\n", USHRT_MAX); 19 printf("unsigned int max = %d\n", UINT_MAX); 20 printf("unsigned long max = %d\n", ULONG_MAX); 21 22 return 0; 23 }
直接计算打印取值范围；
1 #include <stdio.h> 2 /*determine ranges of types*/ 3 main() 4 { 5 /* signed ranges of types*/ 6 7 printf(" signed char min = %d \n", -(char)((unsigned char) ~0 >> 1)); 8 9 printf(" signed char max = %d \n", (char)((unsigned char) ~0 >> 1)); 10 11 printf(" signed short min = %d \n", -(short)((unsigned short) ~0 >> 1)); 12 13 printf(" signed short max = %d \n", (short)((unsigned short) ~0 >> 1)); 14 15 printf(" signed int min = %d \n", -(int)((unsigned int) ~0 >> 1)); 16 17 printf(" signed int max = %d \n", (int)((unsigned int) ~0 >> 1)); 18 19 printf(" signed long min = %d \n", -(long)((unsigned long) ~0 >> 1)); 20 21 printf(" signed long max = %d \n", (long)((unsigned long) ~0 >> 1)); 22 23 24 /*unsigned types*/ 25 26 printf(" unsigned char max = %d \n",(unsigned char) ~0); 27 28 printf(" unsigned int max = %d \n",(unsigned int) ~0); 29 30 printf(" unsigned short max = %d \n",(unsigned short) ~0); 31 32 printf(" unsigned long max = %d \n",(unsigned long) ~0); 33 34 35 return 0; 36 }
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
