Qt QString详解

迈不过友情╰ 2022-10-30 10:23 128阅读 0赞

# 1.QString 常用方法 #

//append 在后面添加字符串，prepend在前面添加字符串
        QString s1 = "张";
        QString s2 = "三";
        QString s3 = s1;
        s1.append(s2);      //s1 = "张三"
        s3.prepend(s2);     //s3 = "三张"
    
        //toUpper,toLower转换大小写
        QString s4 = "Hello,World";
        QString s5,s6;
        s5 = s4.toUpper();      //HELLO,WORLD
        s6 = s4.toLower();      //hello,world
    
        //字符串的个数
        int nCount = s4.count();    //nCount = 11
        nCount = s4.size();         //nCount = 11
        nCount = s4.length();       //nCount = 11
    
        //trimmed去掉字符串首尾的空格，simplified不仅去掉首尾的空格，中间连续的空格也用一个空格代替
        QString s7 = "  QString S7    Are you OK  ？ ";
        QString s8,s9;
        s8 = s7.trimmed();    //s8 = "QString S7    Are you OK  ？"
        s9 = s7.simplified(); //s9 = "QString S7 Are you OK ？"
    
        //indexOf查找字符串首次出现的位置，没找到返回-1，lastIndexOf最后一次出现的位置
        QString s10 = "Are you eOK";
        nCount = s10.indexOf("you");   //4
        nCount = s10.lastIndexOf("e"); //8
    
        //判断是否为空,只有未赋值的字符串isNull返回true
        QString s11,s12 = "";
        bool bRet = s11.isNull(); //true
        bRet = s11.isEmpty();     //true
        bRet = s12.isNull();      //false
        bRet = s12.isEmpty();     //true
    
        //判断是否包含字符串
        s10 = "Are you eOK";
        bRet = s10.contains("you",Qt::CaseInsensitive); //不区分大小写 true
        bRet = s10.contains("YOu",Qt::CaseSensitive);   //区分大小写 false
    
        //判断是否以字符串结尾，字符串开始
        s10 = "Are you eOK";
        bRet = s10.endsWith("eOK",Qt::CaseInsensitive); //不区分大小写 true
        bRet = s10.endsWith("EoK",Qt::CaseInsensitive); //区分大小写 false
        bRet = s10.startsWith("a");                     //缺省为不区分大小写true
    
        //从左边取多少个字符，从右边取多少个字符
        QString x = "Pineapple";
        QString y1 = x.left(4);       // y == "Pine"
        QString y2 = x.right(5);      // y == "apple"
    
        //从字符串中提取 以第一个参数作为分隔符 ，从第二个参数 到 第三个参数的字符串。
        QString str;
        QString csv = "forename,middlename,surname,phone";
        QString path = "/usr/local/bin/myapp";                          // First field is empty
    
        str = csv.section(',', 2, 2);                                   // str == "surname"
        str = path.section('/', 3, 4);                                  // str == "bin/myapp"
        str = path.section('/', 3, 3, QString::SectionSkipEmpty);       // str == "myapp"
    
        //分割字符串
        QStringList list1 = path.split("/");
    
        //字符串 -> 数字
        int number = QString("23").toInt();
        //数字 -> 字符串
        QString strNum = QString::number(23);