QChar中的数据字节比从QChar到QByteArray的数据字节 [英] data bytes in QChar than from QChar to QByteArray

问题描述

我试图在QChar中获取数据（8字节）而不是将其保存到QByteArray中，因为后来我想在我的函数中单独使用每个字节。

 QChar tempVar = *（QChar *）DeviceMsg.DATA; 

预期来自DeviceMsg.DATA的字节类似于00ff22ff55001188



我要找的是

 QByteArray qba; 
 qba.data（）[0] 00 
 qba.data（）[1] ff 
 qba.data（）[2] 22 
 qba.data（）[3 ] ff 
 .. 

这里的问题是



如何从QChar转换为QByteArray？



感谢阅读问题任何帮助将不胜感激

解决方案

这将无法正常工作，因为你的input是一个包含16个字符的字符串（您的示例00ff22ff55001188）（ QChar ）。如果需要由两个字符表示的字节，则必须获得一个字符对并将其转换为一个字节，或者只是将整个字符串转换为64位值并将其拆分为字节。



一个可能的解决方案是（假设 DeviceMsg 是 QString ，16个字符表示64-位十六进制值）：

 QByteArray qba; 
 qba.resize（ 8 ）; 
 qulonglong val = DeviceMsg.toULongLong（NULL， 16 ）; 
  for （ int  i =  0 ; i<  8 ; i ++）
 {
  //  < span class =code-comment>获取低字节并将其存储在字节数组中 
 qba [i] = static_cast< char>（val& 0xFF）; 
  //  下一个字节的移位 
 val>> =  8 ; 
} 

根据有关DeviceMsg的新信息（见下文评论） ）没有必要使用 QChar ，解决方案非常简单（参见 http://doc.qt.io/qt-5/qbytearray.html#QByteArray-1 [ ^ ]）：

 QByteArray qba（（  const   char  *）DeviceMsg.DATA， sizeof （DeviceMsg.DATA））; 

Hi,
I am trying to get data(8 Bytes) in QChar than save it into QByteArray because later i want to use each byte separately in my function.

QChar tempVar=*(QChar*) DeviceMsg.DATA;

expected Bytes from DeviceMsg.DATA would be something like 00ff22ff55001188

what i am looking for is

QByteArray qba;
qba.data()[0]     00
qba.data()[1]     ff
qba.data()[2]     22
qba.data()[3]     ff
..

question here is

how to convert from QChar to QByteArray?

Thanks for reading Question any help would be appreciated

解决方案

This would not work as expected because your input is a string (your example "00ff22ff55001188") containing 16 characters (QChar). If you need the bytes represented by two characters, you must get a character pair and convert it to a byte or just convert the whole string to a 64-bit value and split that into bytes.

A possible solution would be (assuming DeviceMsg is a QString with 16 characaters representing a 64-bit hex value):

QByteArray qba;
qba.resize(8);
qulonglong val = DeviceMsg.toULongLong(NULL, 16);
for (int i = 0; i < 8; i++)
{
    // Get the low byte and store it in the byte array
    qba[i] = static_cast<char>(val & 0xFF);
    // Shift in next byte
    val >>= 8;
}

[EDIT]
According to the new information about DeviceMsg (see below comment) there is no need to use QChar and the solution is quite simple (see http://doc.qt.io/qt-5/qbytearray.html#QByteArray-1[^]):

QByteArray qba((const char *)DeviceMsg.DATA, sizeof(DeviceMsg.DATA));

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