c++ 快速将原始数据转换为十六进制字符串
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Quickly convert raw data to hex string in c++
提问by krb686
I'm reading data from a file and trying to display the raw data as 2 digit hex strings.
我正在从文件中读取数据并尝试将原始数据显示为 2 位十六进制字符串。
I'm using the Qt framework, specifically the QTextEdit.
我正在使用 Qt 框架，特别是 QTextEdit。
I've tried a bunch of different approaches and have almost accomplished what I want it to do, however it has some unexpected errors I don't know anything about.
我尝试了很多不同的方法，几乎完成了我想要它做的事情，但是它有一些我不知道的意外错误。
Currently this is my implementation:
目前这是我的实现：
1) Read in the data:
1）读入数据：
ifstream file (filePath, ios::in|ios::binary|ios::ate);
if (file.is_open())
{
size = file.tellg();
memblock = new char [size+1];
file.seekg(0, ios::beg);
file.read(memblock, size);
file.close();
}
2) Create a single QString that will be used (because QTextEdit requires a QString):
2）创建一个将被使用的 QString（因为 QTextEdit 需要一个 QString）：
QString s;
3) Loop through the array appending each successive character to the QString s.
3) 遍历数组，将每个连续字符附加到 QString s。
int count = 0;
for(i=0;i<size;i++)
{
count++;;
s.append(QString::number(memblock[i], 16).toUpper());
s.append("\t");
if (count == 16)
{
s.append("\n");
count -= 16;
}
}
Now this works fine, except when it reaches a character FF, it appears as FFFFFFFFFFFFFFFF
现在这工作正常，除非当它到达一个字符时FF，它显示为FFFFFFFFFFFFFFFF
So my main questions are:
所以我的主要问题是：
- Why do only the 'FF' characters appear as 'FFFFFFFFFFFFFFFF' instead?
- Is there a way to convert the char data to base 16 strings without using QString::number?
- 为什么只有“FF”字符显示为“FFFFFFFFFFFFFFFF”？
- 有没有办法在不使用 QString::number 的情况下将字符数据转换为基数为 16 的字符串？
I want this implementation to be as fast as possible, so if something like sprintf could work, please let me know, as I would guess that might be faster that QString::number.
我希望这个实现尽可能快，所以如果像 sprintf 这样的东西可以工作，请告诉我，因为我猜这可能比 QString::number 更快。
回答by Pavel Strakhov
QStringcan't be used for binary data. You should use QByteArrayinstead. It can be easily created from char*buffer and can be easily converted to hex string using toHex.
QString不能用于二进制数据。你应该QByteArray改用。它可以很容易地从char*缓冲区创建，并且可以很容易地使用toHex.
QByteArray array(memblock, size);
textEdit->setText(QString(array.toHex()));
回答by Praetorian
QString::numberdoesn't have an overload that takes a char, so your input is being promoted to an int; consequently you're seeing the effects of sign extension. You should be seeing similar behavior for any input greater than 0x7F.
QString::number没有需要 a 的重载char，因此您的输入被提升为int; 因此，您会看到符号扩展的效果。对于大于 的任何输入，您应该会看到类似的行为0x7F。
Try casting the data prior to calling the function.
在调用函数之前尝试转换数据。
s.append(QString::number(static_cast<unsigned char>(memblock[i]), 16).toUpper());
