Arduino C ++ char数组为空，元素被填充

Question

I'am trying to print a char array to serial. The array itself is filled with chars, but as soon as I'am printing the whole array - and not just elements of it - the string printed is empty.

#define MAX_PAYLOAD_SIZE 80
class CmdBuffer {
...
private:
    char buffer[MAX_PAYLOAD_SIZE+1];
    int bufferpointer;
...
};

//In cpp File
String CmdBuffer::readCommand(char data) {
    buffer[++bufferpointer]=data;
    if(data != CMD_EOF) {
       return NULL;
    }
    buffer[++bufferpointer]='\0';
    ...
    for(int i=0; i<bufferpointer; i++) {
        Serial.print(buffer[i]);
    }
    Serial.println("\n-------"); 
    Serial.println(buffer);
    Serial.println("END");  
    ...
}

If the input chars are abcdefg then the output looks like

abcdefg
-------

END

So why can the elements be printed, while the whole array can't?

Answer 1

I suspect it's because you are not assigning the first character:

buffer[++bufferpointer]=data;

Because of the pre-increment, you're missing the first character. It probably contains a null, so it terminates your string right there. To fix it, use post-increment:

buffer[bufferpointer++]=data;