[英]How to pass in a const char* as an argument to an LPCSTR parameter?
I'd like to use this function to call the the PlaySoundA function, but the sound file I am trying to play does not open.我想用这个 function 来调用 PlaySoundA function,但是我要播放的声音文件打不开。
void AudioClass::playAudio(const char* incomingData, const char* filePath)
{
char buffer[100]; // <- danger, only storage for 100 characters.
strncpy_s(buffer, filePath, sizeof(buffer));
strncat_s(buffer, incomingData, sizeof(buffer));
PlaySoundA(buffer, NULL, SND_FILENAME);
}
As I found out, if the argument for the LPCSTR pszSound parameter of PlaySoundA() is given as a string (eg "C:/Users/User/Documents/sound.wav"), ie the full path of the file is given, the sound will play.我发现,如果 PlaySoundA() 的 LPCSTR pszSound 参数的参数以字符串形式给出(例如“C:/Users/User/Documents/sound.wav”),即给出文件的完整路径,声音将播放。
I would like to combine the incomingData parameter (file name) and the filePath parameter, for which I used a buffer.我想将incomingData 参数(文件名)和filePath 参数结合起来,为此我使用了一个缓冲区。
If the file cannot be found, the default system sound should play (it was a beep in my case), but this is no longer the case;如果找不到文件,则应播放默认系统声音(在我的情况下是哔哔声),但不再是这种情况; even though SND_NODEFAULT flag was not set, in which case PlaySoundA() would return silently, without playing the default system sound.
即使未设置 SND_NODEFAULT 标志,在这种情况下 PlaySoundA() 也会静默返回,不会播放默认系统声音。
https://docs.microsoft.com/en-us/previous-versions/dd743680(v%3Dvs.85) https://docs.microsoft.com/en-us/previous-versions/dd743680(v%3Dvs.85)
Is it possible that the argument I am trying to pass in not compatible with LPCSTR pszSound parameter?我试图传递的参数是否可能与 LPCSTR pszSound 参数不兼容?
While running the debugger, the buffer variable seems to hold the whole path (C:/Users/User/Documents/sound.wav\r\n), but why is there a \r\n prefix at the end?运行调试器时,buffer 变量似乎保存了整个路径(C:/Users/User/Documents/sound.wav\r\n),但为什么末尾有 \r\n 前缀?
Definitions:定义:
#define MAX_DATA_LENGTH 255
char incomingData[MAX_DATA_LENGTH];
const char* filePath {"C:/Users/User/Desktop/"};
//Arduino SerialPort object
SerialPort *arduino;
//Audio file AudioClass object
AudioClass* audio;
playAudio() is called here: playAudio() 在这里被调用:
void exampleReceiveData(void)
{
int readResult = arduino->SerialPort::readSerialPort(incomingData, MAX_DATA_LENGTH);
audio->AudioClass::playAudio(incomingData, filePath);
Sleep(10000);
}
EDIT_1: the length of the real file path I use is shorter than 100 characters. EDIT_1:我使用的真实文件路径的长度小于 100 个字符。
EDIT_2: I get this warning: String 'buffer' might not be zero-terminated. EDIT_2:我收到此警告:字符串“缓冲区”可能不是以零结尾的。
The \r\n
at the end comes from the serial port: https://www.arduino.cc/reference/en/language/functions/communication/serial/println末尾的
\r\n
来自串口: https://www.arduino.cc/reference/en/language/functions/communication/serial/println
You can skip the characters when copying:复制时可以跳过字符:
strncat_s(buffer, incomingData, strnlen(incomingData) - 2);
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