c++ - 如何检查文本文件中的特定行是否以特定单词开头

Question

我有一个文本文件，我在其中写入磁盘分区中所有文件的路径。

WriteToFile::WriteToFile(QString path, QString data)
{
    path = "E:/Data.txt";
    QFile file(path);
    if ( file.open(QFile::Append) )
    {
        data += "\r\n";
        QTextStream stream( &file );
        stream << data << endl;
        qDebug() << "Writting: " << data;

    }
}

我只将新路径写入文件中。

void ScanDir::qDirIteratorScanner()
{
    // QString basePath;
    QDirIterator it(this -> basePath, QDir::Files, QDirIterator::Subdirectories);
    while (it.hasNext())
    {
        // QStringList paths;
        paths = scanned();
        QString path = it.next();

        qDebug() << "Collected : " << paths.size();

        if (!paths.contains(path)) {
            WriteToFile writeToFile(basePath, path);
            paths << path;
        }
        else {
            qDebug() << "Already put : " << path;
        }
    }

}

我预计有时会开始扫描分区，但在程序完成扫描分区之前停止程序。我想通过将“LAST-SCAN-POINT”附加到文件中最后一个路径条目的开头来标记我上次停止的位置(如果它是新路径)，或最后一个 if (!paths.contains(path)) (如果我在程序检查路径是否已插入文件时终止程序)

如何检查文本文件中是否存在以 LAST-SCAN-POINT 开头的行

Data.txt

C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7010.idrc
C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7011.idrc
C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7012.idrc
C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7013.idrc
C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7014.idrc
C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7015.idrc
LAST-SCAN-POINT C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7016.idrc
C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7017.idrc
C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7018.idrc
C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7019.idrc

Answer 1

如何使用QString::startsWith method ？例如:

QString path = "LAST-SCAN-POINT C:/Program Files/Adobe/Adobe InDesign CC 2015/Plug-Ins/Layout/(Alignment Panel Resources)/idrc_PNGA/7016.idrc";

if(path.startsWith("LAST-SCAN-POINT ")) {

    qDebug() << "The path starts with 'LAST-SCAN-POINT '";
} else {
    qDebug() << "The path does not start with 'LAST-SCAN-POINT '!";
}