判断操作系统的位数和主机字节序s

实现了2个 函数，判断操作系统的位数和主机字节序

#include <stdio.h>

int show_sys_bit(void);
int show_sys_endian(void);

int main(int argc,char * argv[])
{

 show_sys_bit();
 show_sys_endian();

 return 0; 
}

/*
   获取操作系统的位数
   返回的为实际位数
*/
int show_sys_bit(void)
{
     unsigned int SYS_SIZE = sizeof(void *);

   if ( 4 == SYS_SIZE )
   printf("This system is 32 bit/r/n");
   else if ( 8 == SYS_SIZE )
   printf("This system is 64 bit/r/n");

   return SYS_SIZE*8;
}

/*
   获取主机字节序
   返回0 为小端
   否则  为大端 
*/
int show_sys_endian(void)
{
    union sys_endian
    {
        unsigned short num;
        unsigned char a[2];
    }sys;    

    sys.num = 1;

    if ( 1 == sys.a[0] )
    printf("The host is little_ending/r/n");
    else
    printf("The host is big_ending/r/n");

    return sys.a[0];

}