C语言整数类型的存储空间和取值范围

C语言整数类型的存储空间和取值范围

1. 四种整数类型 char, short, int, long 默认有符号，再加上无符号限制，共8种情况

              char // 字符型，单字节，取值范围：CHAR_MIN - CHAR_MAX
     unsigned char // 无符号字符型，  取值范围：0 - UCHAR_MAX
         short int // 短整型，双字节，取值范围：SHRT_MIN - SHRT_MAX
unsigned short int // 无符号短整型，  取值范围：0 - USHRT_MAX
               int // 整型，四字节，  取值范围：INT_MIN - INT_MAX
      unsigned int // 无符号整型，    取值范围：0 - UINT_MAX
          long int // 长整型，八字节，取值范围：LONG_MIN - LONG_MAX
 unsigned long int // 无符号长整型，  取值范围： 0 - ULONG_MAX

在Linux下测试发现long long，即长长整型与long长整型所表达的效果是一样的！！！

2. 写代码输出整数类型的存储空间和取值范围相关信息
   注意：相关的宏定义在limits.h头文件中，要包含进来！

/* filename: limits.c */
#include <stdio.h>
#include <limits.h>

/*
  compile : gcc limits.c -o limits
      run : ./limits
*/

/* output datatype char, short, int, long
   sizeof, min, max, unsigned max information */
void
out_smmu_info (void)
{
  printf ("Sizeof char is %lu\n", sizeof (char));
  printf ("Min char is %d\n", CHAR_MIN);
  printf ("Max char is %d\n", CHAR_MAX);
  printf ("Max unsigned char is %u\n", UCHAR_MAX);
  printf ("--------------------------------\n");
  printf ("Sizeof short is %lu\n", sizeof (short));
  printf ("Min short is %d\n", SHRT_MIN);
  printf ("Max short is %d\n", SHRT_MAX);
  printf ("Max unsigned short is %u\n", USHRT_MAX);
  printf ("--------------------------------\n");
  printf ("Sizeof int is %lu\n", sizeof (int));
  printf ("Min int is %d\n", INT_MIN);
  printf ("Max int is %d\n", INT_MAX);
  printf ("Max unsigned int is %u\n", UINT_MAX);
  printf ("--------------------------------\n");
  printf ("Sizeof long is %lu\n", sizeof (long));
  printf ("Min long is %ld\n", LONG_MIN);
  printf ("Max long is %ld\n", LONG_MAX);
  printf ("Max unsigned long is %lu\n", ULONG_MAX);
  printf ("--------------------------------\n");
}

/* output char, short, int, long
   min, max, unsigned max value, define myself use hex */
void
out_selfdef_info (void)
{
  printf ("Self def: CHAR_MIN ==> 0X80, %d\n", (char)(0X80));
  printf ("Self def: CHAR_MAX ==> 0X7F, %d\n", (char)(0X7F));
  printf ("Self def: UCHAR_MAX ==> 0XFF, %u\n", (unsigned char)(0XFF));
  printf ("-------------------------------------------------------\n");
  printf ("Self def: SHORT_MIN ==> 0X8000, %d\n", (short)(0X8000));
  printf ("Self def: SHORT_MAX ==> 0X7FFF, %d\n", (short)(0X7FFF));
  printf ("Self def: USHORT_MAX ==> 0XFFFF, %u\n", (unsigned short)(0XFFFF));
  printf ("-------------------------------------------------------\n");
  printf ("Self def: INT_MIN ==> 0X80000000, %d\n", (int)(0X80000000));
  printf ("Self def: INT_MAX ==> 0X7FFFFFFF, %d\n", (int)(0X7FFFFFFF));
  printf ("Self def: UINT_MAX ==> 0XFFFF, %u\n", (unsigned int)(0XFFFFFFFF));
  printf ("-------------------------------------------------------\n");
  printf ("Self def: LONG_MIN ==> 0X8000000000000000, %ld\n",
	  (long)(0X8000000000000000));
  printf ("Self def: LONG_MAX ==> 0X7FFFFFFFFFFFFFFF, %ld\n",
	  (long)(0X7FFFFFFFFFFFFFFF));
  printf ("Self def: ULONG_MAX ==> 0XFFFFFFFFFFFFFFFF, %lu\n",
	  (unsigned long)(0XFFFFFFFFFFFFFFFF));
  printf ("-------------------------------------------------------\n");
}

/**/
int
main (int argc, char *argv[])
{
  out_smmu_info ();
  out_selfdef_info ();
  return 0;
}
/* --(:-:)-- */

3. 编译运行，输出结果如下：

gwsong@ubuntu:~/works/zoo/tmp$ gcc limits.c -o limits
gwsong@ubuntu:~/works/zoo/tmp$ ./limits
Sizeof char is 1
Min char is -128
Max char is 127
Max unsigned char is 255
--------------------------------
Sizeof short is 2
Min short is -32768
Max short is 32767
Max unsigned short is 65535
--------------------------------
Sizeof int is 4
Min int is -2147483648
Max int is 2147483647
Max unsigned int is 4294967295
--------------------------------
Sizeof long is 8
Min long is -9223372036854775808
Max long is 9223372036854775807
Max unsigned long is 18446744073709551615
--------------------------------
Self def: CHAR_MIN ==> 0X80, -128
Self def: CHAR_MAX ==> 0X7F, 127
Self def: UCHAR_MAX ==> 0XFF, 255
-------------------------------------------------------
Self def: SHORT_MIN ==> 0X8000, -32768
Self def: SHORT_MAX ==> 0X7FFF, 32767
Self def: USHORT_MAX ==> 0XFFFF, 65535
-------------------------------------------------------
Self def: INT_MIN ==> 0X80000000, -2147483648
Self def: INT_MAX ==> 0X7FFFFFFF, 2147483647
Self def: UINT_MAX ==> 0XFFFF, 4294967295
-------------------------------------------------------
Self def: LONG_MIN ==> 0X8000000000000000, -9223372036854775808
Self def: LONG_MAX ==> 0X7FFFFFFFFFFFFFFF, 9223372036854775807
Self def: ULONG_MAX ==> 0XFFFFFFFFFFFFFFFF, 18446744073709551615
-------------------------------------------------------

4. 用十六进制自定义取值范围清晰明了，不同情况下可以选择不同长度的整数数据类型
   下一步研究一下其他数据类型的存储长度和相关信息。