QRegularExpression 是Qt 5.0才引进的，相对于QRegExp，QRegularExpression class修复了很多bug，提高了效率，提供了对Perl的RegEx几乎全面兼容的搜索引擎。简单说，QRegExp年久失修，bug较多，使用时建议使用QRegularExpression。
注意：若在正则表达式中需要用到”\”，需要在它前面补一个转义字符”\”，因为”\”在字符串中是一个转义字符会将后面的字符换算成ASCII码进行转义。所以如果要将”\”传递到正则当中就需要多添加一个”\”做转义。

#include <QCoreApplication>
#include <QDebug>
#include <QRegExp>
#include <QRegularExpression>
#include <QRegularExpressionMatch>

int main(int argc,char *argv[])
{   
    QString pattern1 = ".*=\\d*";
    QString pattern2 = "[a-z]*=\\d*";
    QString pattern3 = "\\w+";
    QString pattern4 = "(.+)=(.+)";

    QString test1("a=123");
    QString test2("-\r\na=123abc");
    QString test3("-_%\r\na=1abc-_%\r\na=12abc-_%\r\na=123abc-_%\r\na=1234abc");
    QString test4("hello world,hello qt");

    //test="a=123",pattern=".*=\\d*"
    QRegExp regExp(pattern1);
    qDebug()<<regExp.exactMatch(test1);//true

    //test="a=-\r\na=123abc",pattern="[a-z]*=\\d*"
    regExp.setPattern(pattern1);
    int pos = test2.indexOf(regExp);
    int matchedLen = regExp.matchedLength();
    QStringList capTexts = regExp.capturedTexts();
    qDebug()<<pos<<","<<matchedLen<<","<<capTexts;//0,8,("-\r\na-123")

    //test="-_%\r\na=1abc-_%\r\na=12abc-_%\r\na=123abc-_%\r\na=1234abc",pattern="[a-z]*=\\d*"
    regExp.setPattern(pattern2);
    //只会找到第一个就停止了
    pos = test3.indexOf(regExp);
    matchedLen = regExp.matchedLength();
    capTexts = regExp.capturedTexts();
    qDebug()<<pos<<","<<capTexts.length()<<","<<capTexts;//5,3,1,("a=1")

    //test="-_%\r\na=1abc-_%\r\na=12abc-_%\r\na=123abc-_%\r\na=1234abc",pattern="[a-z]*=\\d*"
    regExp.setPattern(pattern2);
    //替换所有，并返回该字符串的引用
    qDebug()<<test3.replace(regExp,"xyz");//-_%\r\nxyzabc-_%\r\nxyzabc-_%\r\nxyzabc-_%\r\nxyzabc"
    qDebug()<<test3;//-_%\r\nxyzabc-_%\r\nxyzabc-_%\r\nxyzabc-_%\r\nxyzabc"

//////////////////////////////////////////////////////////////////////////////////////////////////////

    //test="hello world,hello qt",pattern="\\w+"
    //Since: Qt 5.0
    QRegularExpression regularExpression(pattern3);
    int index = 0;
    QRegularExpressionMatch match;
    do {
        match = regularExpression.match(test4,index);
        if(match.hasMatch()) {
            index = match.capturedEnd();
            qDebug()<<"("<<match.capturedStart()<<","<<index<<") "<<match.captured(0);
            //(0,5) "hello"
            //(6,11) "world"
            //(13,18) "hello"
            //(19,21) "qt"
        } else {
            break;
        }
    } while(index < test4.length());

    //test="a=-\r\na=123abc",pattern="\\w+"
    qDebug()<<test2.indexOf(regularExpression);//3

    //test="hello world,pattern="\\w+"
    qDebug()<<test4.replace(regularExpression,"x");//"x x,x x"

    //正则表达式分组
    //test="a=123",pattern="(.+)=(.+)"
    regularExpression.setPattern(pattern4);
    match = regularExpression.match(test1);
    qDebug()<<match.captured(0);//"a=123"
    qDebug()<<match.captured(1);//"a"
    qDebug()<<match.captured(2);//"123"
    qDebug()<<match.capturedTexts();//("a=100","a","100")
    return 0;
}