big endian vs little endian

　　今天在网上看见有人讨论big endian和little endian的问题，觉得以下是正确的，并编程验证：

　　Big endian machine: It thinks the first byte it reads is the biggest.
Little endian machine: It thinks the first byte it reads is the littlest.
举个例子，从内存地址0x0000开始有以下数据：

 0x0000     0x12
 0x0001     0x34
 0x0002     0xab
 0x0003     0xcd
如果我们去读取一个地址为0x0000的四个字节变量，若字节序为big-endian，则读出
结果为0x1234abcd；若字节序位little-endian，则读出结果为0xcdab3412.
如果我们将0x1234abcd写入到以0x0000开始的内存中，则结果为
        big-endian     little-endian
0x0000     0x12              0xcd
0x0001     0x34              0xab
0x0002     0xab              0x34
0x0003     0xcd              0x12
x86系列CPU都是little-endian的字节序.
以下是验证：

#include
#include
int main(int argc, char **argv)
{
        if(G_BYTE_ORDER == G_LITTLE_ENDIAN)
        {
                printf("the pc you use is in little mode!\n");
        }
        else
        {
                printf("the pc you use is in big mode!\n");
        }
        int a = 0x12345678;
        printf("%x's big mode is %x\n", a, GINT_TO_BE(a));
        printf("%x's little mode is %x\n", a, a);
        return 0;
}

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

以下是结果：

the pc you use is in little mode!
12345678's big mode is 78563412
12345678's little mode is 12345678