如果通过字符串表示std::string您可以使用以下方法进行操作：

QString QString::fromStdString(const std::string &
str)

std::string str = "Hello world";
QString qstr = QString::fromStdString(str);

如果通过字符串你的意思是 Ascii 编码const char *，那么你可以使用这个方法：

QString QString::fromAscii(const char * str, int size =
-1)

const char* str = "Hello world";
QString qstr = QString::fromAscii(str);

如果您使用可以使用QTextCodec::codecForLocale()const char *读取的系统编码进行编码，那么您应该使用此方法：

QString QString::fromLocal8Bit(const char * str, int size =
-1)

const char* str = "za偶贸艂膰 g臋艣l膮 ja藕艅";      // latin2 source file and system encoding
QString qstr = QString::fromLocal8Bit(str);

如果您使用const char *的是 UTF8 编码，则需要使用此方法：

QString QString::fromUtf8(const char * str, int size =
-1)

const char* str = read_raw("hello.txt"); // assuming hello.txt is UTF8 encoded, and read_raw() reads bytes from file into memory and returns pointer to the first byte as const char*
QString qstr = QString::fromUtf8(str);

还有const ushort *包含 UTF16 编码字符串的方法：

QString QString::fromUtf16(const ushort * unicode, int size =
-1)

const ushort* str = read_raw("hello.txt"); // assuming hello.txt is UTF16 encoded, and read_raw() reads bytes from file into memory and returns pointer to the first byte as const ushort*
QString qstr = QString::fromUtf16(str);