C 标准库 – <limits.h>

limits.h 头文件决定了各种变量类型的各种属性。定义在该头文件中的宏限制了各种变量类型（比如 char、int 和 long）的值。

这些限制指定了变量不能存储任何超出这些限制的值，例如一个无符号可以存储的最大值是 255。

库宏

下面的值是特定实现的，且是通过 #define 指令来定义的，这些值都不得低于下边所给出的值。

实例

下面的实例演示了 limit.h 文件中定义的一些常量的使用。

#include <stdio.h>
#include <limits.h>

int main()
{

   printf("The number of bits in a byte %d\n", CHAR_BIT);

   printf("The minimum value of SIGNED CHAR = %d\n", SCHAR_MIN);
   printf("The maximum value of SIGNED CHAR = %d\n", SCHAR_MAX);
   printf("The maximum value of UNSIGNED CHAR = %d\n", UCHAR_MAX);

   printf("The minimum value of SHORT INT = %d\n", SHRT_MIN);
   printf("The maximum value of SHORT INT = %d\n", SHRT_MAX); 

   printf("The minimum value of INT = %d\n", INT_MIN);
   printf("The maximum value of INT = %d\n", INT_MAX);

   printf("The minimum value of CHAR = %d\n", CHAR_MIN);
   printf("The maximum value of CHAR = %d\n", CHAR_MAX);

   printf("The minimum value of LONG = %ld\n", LONG_MIN);
   printf("The maximum value of LONG = %ld\n", LONG_MAX);
  
   return(0);
}

让我们编译和运行上面的程序，这将产生下列结果：

The number of bits in a byte 8
The minimum value of SIGNED CHAR = -128
The maximum value of SIGNED CHAR = 127
The maximum value of UNSIGNED CHAR = 255
The minimum value of SHORT INT = -32768
The maximum value of SHORT INT = 32767
The minimum value of INT = -32768
The maximum value of INT = 32767
The minimum value of CHAR = -128
The maximum value of CHAR = 127
The minimum value of LONG = -2147483648
The maximum value of LONG = 2147483647