c - typedef 枚举 : Different values for one member

Question

我想知道是否可以为 typedef 枚举的同一成员分配不同的值，如下所示......:

typedef enum {

    START   = 0x01,
    DATA    = 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
    CRC     = 0x0A, 0x0B

}bytes_t;

...所以我以后可以像这样使用它:

bytesReceived++;                        // incremented for every received byte

switch (bytesReceived) {

    case START:
        dPkg->startByte = dpkgRxBuffer[bytesReceived];              
        break;

    case DATA:
        dPkg->data = dpkgRxBuffer[bytesReceived];
        break;

    case CRC:
        dPkg->crc = dpkgRxBuffer[bytesReceived];
        break;

}

因此，如果在循环中调用，程序将执行DATA 情况八次。这有效吗？这只是第一个想法，因此遗憾的是我无法为您提供更多背景信息。

Answer 1

这是不可能的。枚举是一个具有不同值的常量。
使用多个案例:

typedef enum {
    START   = 0x01,
    DATA_2  = 0x02, 
    DATA_3  = 0x03,
    DATA_4  = 0x04,
    ...
    DATA_9  = 0x09,
    CRC_1   = 0x0A, 
    CRC_2   = 0x0B
}bytes_t;

switch (variable) {
    case START:
        dPkg->startByte = dpkgRxBuffer[bytesReceived];              
        break;
    case DATA_2:
    case DATA_3:
    ...
    case DATA_9:
        dPkg->data = dpkgRxBuffer[bytesReceived];
        break;
    case CRC_1:
    case CRC_2:
        dPkg->crc = dpkgRxBuffer[bytesReceived];
        break;
}

或使用 if 与范围:

typedef enum {
    START   = 0x01,
    DATA_START  = 0x02, 
    DATA_STOP   = 0x09,
    CRC_1     = 0x0A, 
    CRC_2     = 0x0B
}bytes_t;

if (variable == START) {
        dPkg->startByte = dpkgRxBuffer[bytesReceived];
} else if (DATA_START <= variable && variable <= DATA_STOP) {
        dPkg->data = dpkgRxBuffer[bytesReceived];
} else if (variable == CRC_1 || variable == CRC_2) {
        dPkg->crc = dpkgRxBuffer[bytesReceived];
}