Big-endian和Little-endian

简而言之：

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 0x23 0xab

0x0002 0xab 0x34

0x0003 0xcd 0x12

x86系列CPU都是little-endian的字节序.