QString、QStringList 类的使用

一、QString类

1、QString转换string

string s = qstr.toStdString();

2、string转换QString

QString qstr2 = QString::fromStdString(s);

3、字符串连接函数

(1) QString也重载的+和+=运算符。这两个运算符可以把两个字符串连接到一起。
(2) QString的append()函数则提供了类似的操作，例如：

   str = "User: "; 
   str.append(userName); 
   str.append("\n");

4、获取字符在字符串中的位置（类似string.find）

QString x = "sticky question"; 
QString y = "sti"; 
   x.indexOf(y);               // returns 0 
   x.indexOf(y, 1);            // returns 10 
   x.indexOf(y, 10);           // returns 10 
   x.indexOf(y, 11);           // returns -1

5、获取字符在字符串中最后出现的位置（类似string.rfind）

int pos = fileDir.lastIndexOf("\\");

6、获取子字符串（类似string.substr）

QString QString::mid(int position, int n = -1) const

参数：
position：指定截取字符串的起始位置(postion超出字符串长度时，返回null字符 )
n：指定截取字符串长度(自postion开始的可用字符串小于n，or n== -1，返回自position开始的全部字符串)

示例：QString fileName = fileDir.mid(pos+1);

7、求字符串的长度，返回值为INT型

fileName.length()

8、字符串组合QString::sprintf()

QString str;
str.sprintf("%s","Welcome ");     //str = "Welcome "
str.sprintf("%s"," to you! ");      //str = " to you! "
str.sprintf("%s %s","Welcome "," to you! ");     //str = "Welcome  to you! ";

9、字符串组合QString::arg()

QString str;
str = QString("%1 was born in %2.").arg("Joy").arg(1993);     //str =  "Joy was born in 1993.";

二、QStringList类

QStringList fileList = QFileDialog::getOpenFileNames(this,tr("Get audio files"),
        QDesktopServices::storageLocation(QDesktopServices::MusicLocation),tr("Music (*.mp3 *.wav *.aac)"));

    int index = fileList.size();
    qDebug("index:%d!", index);

    QList<QString>::Iterator it = fileList.begin();
    for(; it != fileList.end(); it++)
    {
        QString fileDir = *it;
        //std::string s_fileDir = fileDir.toStdString();
        //int pos = s_fileDir.rfind("\\");
        //std::string s_fileName = s_fileDir.substr(pos+1);
        //QString fileName = QString::fromStdString(s_fileName);
        int pos = fileDir.lastIndexOf("\\");
        QString fileName = fileDir.mid(pos+1);

        AddFileToPlayList(fileName, fileDir, "01:01:01");
    }