如何使用qt獲取複雜的子字符串？

Question

我在QT和C++上工作。作爲測試項目的一部分，我需要從複雜和長字符串中獲取子字符串，基本上它是網頁的源。如果我的問題看起來很瑣碎，那將是因爲我是一個天真的qt程序員，並且對正則表達式的經驗不足。

字符串： 「url_encoded_fmt_stream_map」：「類型=視頻％2Fwebm％3B +編解碼器的％3D％22vp8.0％2C + Vorbis的％22 \ u0026quality =介質\ u0026itag = 43 \ u0026url = 的https％3A ％2F％2Fr2 --- sn-ci5gup-qxaz.googlevideo.com％2Fvideoplayback％3Fmime％3Dvideo％252Fwebm％26key％3Dyt6％26initcwndbps％3D386250％26pcm2cms％3Dyes％26requiressl％3Dyes％26signature％3D05FB41F2F9FF5490841C7B9F40748FC4B8F505A3.0D81AB0745519F179CBF4468D2412C2240DC72F0％26ratebypass％3Dyes ％26fexp％3D3300119％252C3300131％252C3313268％252C9405961％252C9416126％252C9416891％252C9419451％252C9422342％252C9422596％252C9427790％252C9428398％252C9431012％252C9433096％252C9433380％252C9433855％252C9433946％252C9434332％252C9435526％252C9435667％252C9435876％252C9436270％252C9436607％252C9436834％252C9436872 ％252C9436973％252C9437066％252C9437553％252C9437742％（252C） 9438326％252C9439652％252C9439979％252C9440048％252C9440552％252C9440651％26ms％3Dau％26mt％3D1467900993％26sparams％3Ddur％252Cid％252Cinitcwndbps％252Cip％252Cipbits％252Citag％252Clmt％252Cmime％252Cmm％252Cmn％252Cms％252Cmv％252Cpcm2cms％252Cpl％ 252Cratebypass％252Crequiressl％252Csource％252Cupn％252Cexpire％26mv％3DM％26ip％3D182.68.203.45％26id％3DO-AMB0Fggb71vKhXSdQqcOPdLeb9v0n2GaibsWg_W5L5b7％26毫米％3D31％26mn％3Dsn-ci5gup-qxaz％26upn％3Dfri9F8GP9uA％26source％3Dyoutube％26itag％ 3D43％26pl％3D20％26lmt％3D1445550849945309％26expire％3D1467922869％26sver％3D3％26ipbits％3D0％26dur％3D0.000，類型=視頻％2Fmp4％3B +編解碼器的％3D％22avc1.42001E％2C + mp4a.40.2％ 22 \ u0026quality = medium \ u0026itag = 18 \ u0026url = https％3A％2F％2Fr2 --- sn-ci5gup-qxaz.googlevideo.com％2Fvideoplayback％3Fmime％3Dvideo％252Fmp4％26key％3Dyt6％26initcwndbps％3D386250％ 26pcm2cms％3Dyes％26requiressl％3Dyes％26signature％3D4C90C634F68098572BDCA7D5B7946F8A49A17369.D4AB7172922F499596226BA335BDF0B4519A4AC6％26ratebypass％3Dyes％26fexp％3D33001 19％252C3300131％252C3313268％252C9405961％252C9416126％252C9416891％252C9419451％252C9422342％252C9422596％252C9427790％252C9428398％252C9431012％252C9433096％252C9433380％252C9433855％252C9433946％252C9434332％252C9435526％252C9435667％252C9435876％252C9436270％252C9436607％252C9436834％252C9436872％252C9436973％ 252C9437066％252C9437553％252C9437742％252C9438326％252C9439652％252C9439979％252C9440048％252C9440552％252C9440651％26ms％3Dau％26mt％3D1467900993％26sparams％3Ddur％252Cid％252Cinitcwndbps％252Cip％252Cipbits％252Citag％252Clmt％252Cmime％252Cmm％252Cmn％252Cms％ 252Cmv％252Cpcm2cms％252Cpl％252Cratebypass％252Crequiressl％252Csource％252Cupn％252Cexpire％26mv％3DM％26ip％3D182.68.203.45％26id％3DO-AMB0Fggb71vKhXSdQqcOPdLeb9v0n2GaibsWg_W5L5b7％26毫米％3D31％26mn％3Dsn-ci5gup-qxaz％26upn％3Dfri9F8GP9uA％ 26source％3Dyoutube％26itag％3D18％26pl％3D20％26lmt％3D1465194153116908％26expire％3D1467922869％26sver％3D3％26ipbits％3D0％26dur％3D207.354，類型=視頻％2F3gpp％3B +編解碼器的％3D％22mp4v.20.3％ 2C + mp4a.40.2％22 \ u0026quality = small \ u0026itag = 36 \ u0026url =

上面的字符串是我的完整字符串和類似模式的重要組成部分。這個網頁來源有許多編碼的網址，我需要分開。下面是我想要分開的東西。

SUBSTRING：

HTTPS％3A％2F％2Fr2 --- sn-ci5gup-qxaz.googlevideo.com％2Fvideoplayback％3Fmime％3Dvideo％252Fwebm％26key％3Dyt6％26initcwndbps％3D386250％26pcm2cms％ 3Dyes％26requiressl％3Dyes％26signature％3D05FB41F2F9FF5490841C7B9F40748FC4B8F505A3.0D81AB0745519F179CBF4468D2412C2240DC72F0％26ratebypass％3Dyes％26fexp％3D3300119％252C3300131％252C3313268％252C9405961％252C9416126％252C9416891％252C9419451％252C9422342％252C9422596％252C9427790％252C9428398％252C9431012％252C9433096％252C9433380％252C9433855％252C9433946％ 252C9434332％252C9435526％252C9435667％252C9435876％252C9436270％252C9436607％252C9436834％252C9436872％252C9436973％252C9437066％252C9437553％252C9437742％252C9438326％252C9439652％252C9439979％252C9440048％252C9440552％252C94406 51％26ms％3Dau％26mt％3D1467900993％26sparams％3Ddur％252Cid％252Cinitcwndbps％252Cip％252Cipbits％252Citag％252Clmt％252Cmime％252Cmm％252Cmn％252Cms％252Cmv％252Cpcm2cms％252Cpl％252Cratebypass％252Crequiressl％252Csource％252Cupn％252Cexpire％ 26mv％3DM％26ip％3D182.68.203。45％26id％3DO-AMB0Fggb71vKhXSdQqcOPdLeb9v0n2GaibsWg_W5L5b7％26毫米％3D31％26mn％3Dsn-ci5gup-qxaz％26upn％3Dfri9F8GP9uA％26source％3Dyoutube％26itag％3D43％26pl％3D20％26lmt％3D1445550849945309％26expire％3D1467922869％26sver％3D3％26ipbits％ 3D0％26dur％3D0.000，type = video％2Fmp4％3B + codecs％3D％22avc1.42001E％2C + mp4a.40.2％22

請幫助並建議如何使用QT，C++，常用表達。我不希望使用任何其他編程語言。 謝謝&此致敬禮。

Answer 1

在Qt中有用於處理字符串的類QString。您應該學習QString文檔部分：Manipulating String Data和Querying String Data。也許，contains()方法QString類足以解決您的問題。

UPD：

簡單的例子與子操縱：

#include <QCoreApplication> 
#include <QDebug> 

int main(int argc, char *argv[]) 
{ 
    QCoreApplication a(argc, argv); 

    QString bigString = "BigString BigString SubString BigString"; 
    QString subString = "SubString"; 

    bool containsFlag = bigString.contains(subString, Qt::CaseSensitive); 
    int index = bigString.indexOf(subString, 0, Qt::CaseSensitive); 

    qDebug() << "Length of subString: " << subString.length(); 
    qDebug() << "SubString contains in bigString: " << containsFlag; 
    qDebug() << "SubString index in bigString: " << index; 

    return a.exec(); 
} 

正如你所看到的，你可以決定是否subString包含bigString。當然，您可以在bigString中確定subString的索引。 你可以把你自己的數據放在bigString和subString。