C++ 将 QString 转换为无符号字符数组
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Convert QString into unsigned char array
提问by samoncode
I have a very basic question here. I tried googling for a while, because there are a lot of similar questions but none of the solutions worked for me.
我在这里有一个非常基本的问题。我尝试谷歌搜索了一段时间，因为有很多类似的问题，但没有一个解决方案对我有用。
here is a code snippet that shows the problem:
这是一个显示问题的代码片段：
QString test = "hello";
unsigned char* test1 = (unsigned char*) test.data();
unsigned char test2[10];
memcpy(test2,test1,test.size());
std::cout<<test2;
I try to fit the QString into the unsigned char array but the output I get is always just 'h'.
我尝试将 QString 放入无符号字符数组中，但我得到的输出始终只是“h”。
Can anyone tell me what is going wrong here?
谁能告诉我这里出了什么问题？
回答by 4pie0
Problem is in that QString.data()returns a QChar*but you want const char*
问题在于QString.data()返回一个QChar*但你想要const char*
QString test = "hello";
unsigned char test2[10];
memcpy( test2, test.toStdString().c_str() ,test.size());
test2[5] = 0;
qDebug() << (char*)test2;
^^^
this is necessary becuase otherwise
just address is printed, i.e. @0x7fff8d2d0b20
The assignment
那作业
unsigned char* test1 = (unsigned char*) test.data();
and trying to copy
并试图复制
unsigned char test2[10];
memcpy(test2,test1,test.size());
is wrong, because QCharis 16 bit entityand as such trying to copy it will terminate because of 0 byte just after 'h'.
是错误的，因为QChar是 16 位实体，因此尝试复制它会因为'h'.
回答by hank
In the second line you're trying to cast QChar*to (unsigned char*)which is completely wrong.
在第二行中，您试图将其强制QChar*转换(unsigned char*)为完全错误的。
Try this:
尝试这个：
QString test = "hello";
QByteArray ba = test.toLocal8Bit();
unsigned char *res = (unsigned char *)strdup(ba.constData());
std::cout << res << std::endl;
