如何将无符号 16 位和无符号 32 位整数编码为无符号 8 位内存数组?

Question

我知道如何进行位移位，但我的值似乎偏离了边缘，我失去了原始值，以换取试图保留 8 位。

Answer 1

对于无符号的 16 位整数：

unsigned short val16 = 0x1234;
unsigned char enc[2];
enc[0] = val16 & 0xff;              // stores 0x34 to enc[0]
enc[1] = val16 >> 8 & 0xff;         // stores 0x12 to enc[1]

对于无符号 32 位整数：

unsigned int val32 = 0x12345678;
unsigned char enc[4];
enc[0] = val32 & 0xff;              // stores 0x78 to enc[0]
enc[1] = val32 >> 8 & 0xff;         // stores 0x56 to enc[1]
enc[2] = val32 >> 16 & 0xff;        // stores 0x34 to enc[2]
enc[3] = val32 >> 24 & 0xff;        // stores 0x12 to enc[3]

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更新

与十进制文字完全相同的代码是：

unsigned short val16 = 4660;       // 4660 = 0x1234
unsigned char enc[2];
enc[0] = val16 & 255;
enc[1] = val16 >> 8 & 255;

和

unsigned int val32 = 305419896;    // 305419896 = 0x12345678
unsigned char enc[4];
enc[0] = val32 & 255;
enc[1] = val32 >> 8 & 255;
enc[2] = val32 >> 16 & 255;
enc[3] = val32 >> 24 & 255;