QString str;
int numInt;
double numDouble;

str=QString::number(numInt);//int转换为QString
str=QString::number(numDouble, 10, 3);//double转换为QString 10进制 保留3位有效数字

QString num;
int numInt;
double numDouble;

numInt=num.toInt();//QString转换为int
numDouble=num.toDouble();//QString转换为double

QString str;
str=QString::fromLocal8Bit("D:/数据集")