翻译强力驱动I am reading a directories content using QDir::entryList(). The filenames within are structured like this:
index_randomNumber.pngI need them sorted by index, the way the Windows Explorer would sort the files so that I get
0_0815.png 1_4711.png 2_2063.png ...instead of what the sorting by QDir::Name gives me:
0_0815.png 10000_6661.png 10001_7401.png ...Is there a built-in way in Qt to achieve this and if not, what's the right place to implement it?
If you want to use QCollator to sort entries from the list of entries returned by QDir::entryList, you can sort the result with std::sort():
dir.setFilter(QDir::Files | QDir::NoSymLinks); dir.setSorting(QDir::NoSort); // will sort manually with std::sort auto entryList = dir.entryList(); QCollator collator; collator.setNumericMode(true); std::sort( entryList.begin(), entryList.end(), [&collator](const QString &file1, const QString &file2) { return collator.compare(file1, file2) < 0; });According to The Badger's comment, QCollator can also be used directly as an argument to std::sort, replacing the lambda, so the last line becomes:
std::sort(entryList.begin(), entryList.end(), collator);Qt didn't have natural sort implementation until Qt 5.2, see this feature request.
Since Qt 5.2 there is QCollator which allows natural sort when numeric mode is enabled.
Yes it is possible.
In order to do that you need to specify the flag LocaleAware when constructing the QDir. object. The constructor is
QDir(const QString & path, const QString & nameFilter, SortFlags sort = SortFlags( Name | IgnoreCase ), Filters filters = AllEntries)You can also use
QDir dir; dir.setSorting(QDir::LocaleAware);inline int findNumberPart(const QString& sIn) { QString s = ""; int i = 0; bool isNum = false; while (i < sIn.length()) { if (isNum) { if (!sIn[i].isNumber()) break; s += sIn[i]; } else { if (sIn[i].isNumber()) s += sIn[i]; } ++i; } if (s == "") return 0; return s.toInt(); } bool naturalSortCallback(const QString& s1, const QString& s2) { int idx1 = findNumberPart(s1); int idx2 = findNumberPart(s2); return (idx1 < idx2); } int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); QDir dir(MYPATH); QStringList list = dir.entryList(QDir::AllEntries | QDir::NoDotAndDotDot); qSort(list.begin(), list.end(), naturalSortCallback); foreach(QString s, list) qDebug() << s << endl; return a.exec(); }Qt doesn't support natural sorting natively, but it can be quite easily implemented. For example, this can be used to sort a QStringList:
struct naturalSortCompare { inline bool isNumber(QChar c) { return c >= '0' && c <= '9'; } inline bool operator() (const QString& s1, const QString& s2) { if (s1 == "" || s2 == "") return s1 < s2; // Move to the first difference between the strings int startIndex = -1; int length = s1.length() > s2.length() ? s2.length() : s1.length(); for (int i = 0; i < length; i++) { QChar c1 = s1[i]; QChar c2 = s2[i]; if (c1 != c2) { startIndex = i; break; } } // If the strings are the same, exit now. if (startIndex < 0) return s1 < s2; // Now extract the numbers, if any, from the two strings. QString sn1; QString sn2; bool done1 = false; bool done2 = false; length = s1.length() < s2.length() ? s2.length() : s1.length(); for (int i = startIndex; i < length; i++) { if (!done1 && i < s1.length()) { if (isNumber(s1[i])) { sn1 += QString(s1[i]); } else { done1 = true; } } if (!done2 && i < s2.length()) { if (isNumber(s2[i])) { sn2 += QString(s2[i]); } else { done2 = true; } } if (done1 && done2) break; } // If none of the strings contain a number, use a regular comparison. if (sn1 == "" && sn2 == "") return s1 < s2; // If one of the strings doesn't contain a number at that position, // we put the string without number first so that, for example, // "example.bin" is before "example1.bin" if (sn1 == "" && sn2 != "") return true; if (sn1 != "" && sn2 == "") return false; return sn1.toInt() < sn2.toInt(); } };Then usage is simply:
std::sort(stringList.begin(), stringList.end(), naturalSortCompare());