判断大端小端模式

 1 #include <stdio.h>
 2 
 3 #define BIG_ENDIAN     1
 4 #define LITTEL_ENDIAN  0
 5 
 6 int big_littel_endian(void)
 7 {
 8     union num
 9     {
10         int a;
11         char b[4];
12     }c;
13     
14     c.a = 0x1234;
15     
16     if(c.b[0] == 0x34)
17     {
18         return LITTEL_ENDIAN;
19     }
20     else
21     {
22         return BIG_ENDIAN;
23     }
24     
25 }
26 
27 int main()
28 {
29     int cpu;
30     
31     cpu = big_littel_endian();
32     
33     if(cpu == LITTEL_ENDIAN)
34         printf("cpu is Little_endian.\n");
35     else
36         printf("cpu is Big_endian.\n");
37 }