QString

string to qstring

qs = QString::fromStdString(s);

数字转字符串

int i = 42;
QString s = QString::number(i);

字符串转数字

QString Abcd = "123.5 Kb";
Abcd.split(" ")[0].toInt();    //convert the first part to Int
Abcd.split(" ")[0].toDouble(); //convert the first part to double
Abcd.split(" ")[0].toFloat();  //convert the first part to float

bool flag;
double v = Abcd.split(" ")[0].toDouble(&flag); 
if(flag){
  // use v
}

To char*

QString str1 = "Test";
QByteArray ba = str1.toLocal8Bit();
const char *c_str2 = ba.data();

QString转QByteArray

char convertCharToHex(char ch)
{
	if((ch >= '0') && (ch <= '9'))
		return ch-0x30;
	else if((ch >= 'A') && (ch <= 'F'))
		return ch-'A'+10;
	else if((ch >= 'a') && (ch <= 'f'))
		return ch-'a'+10;
	else return (-1);
}

void convertStringToHex(const QString &str, QByteArray &byteData)
{
	int hexdata,lowhexdata;
	int hexdatalen = 0;
	int len = str.length();
	byteData.resize(len/2);
	char lstr,hstr;
	for(int i=0; i<len; )
	{
		//char lstr,
		hstr=str[i].toLatin1();
		if(hstr == ' ')
		{
			i++;
			continue;
		}
		i++;
		if(i >= len)
			break;
		lstr = str[i].toLatin1();
		hexdata = convertCharToHex(hstr);
		lowhexdata = convertCharToHex(lstr);
		if((hexdata == 16) || (lowhexdata == 16))
			break;
		else
			hexdata = hexdata*16+lowhexdata;
		i++;
		byteData[hexdatalen] = (char)hexdata;
		hexdatalen++;
	}
	byteData.resize(hexdatalen);
}

QString testData="a503930000000200000008746ed16a156655a6";
QByteArray arr = m_socket->readAll();
arr = testData.toUtf8().toHex();
convertStringToHex(testData,arr);
char* p = (char*)arr.data();