diff --git a/src/core/authinfo.cpp b/src/core/authinfo.cpp
--- a/src/core/authinfo.cpp
+++ b/src/core/authinfo.cpp
@@ -332,9 +332,7 @@
         return false;
     }
 
-    for (LoginList::ConstIterator it = l.begin(); it != l.end(); ++it) {
-        const AutoLogin &log = *it;
-
+    for (const AutoLogin &log : l) {
         if ((mode & defaultOnly) == defaultOnly &&
                 log.machine == QLatin1String("default") &&
                 (login.login.isEmpty() || login.login == log.login)) {
diff --git a/src/core/desktopexecparser.cpp b/src/core/desktopexecparser.cpp
--- a/src/core/desktopexecparser.cpp
+++ b/src/core/desktopexecparser.cpp
@@ -167,8 +167,8 @@
     case 'N':
     case 'D':
         option += 'a' - 'A';
-        for (QList<QUrl>::ConstIterator it = urls.begin(); it != urls.end(); ++it) {
-            subst(option, *it, ret);
+        for (const QUrl &url : urls) {
+            subst(option, url, ret);
         }
         break;
     case '%':
@@ -449,9 +449,9 @@
 {
     // Remove parameters and/or trailing spaces.
     const QStringList args = KShell::splitArgs(execLine);
-    for (QStringList::ConstIterator it = args.begin(); it != args.end(); ++it) {
-        if (!(*it).contains(QLatin1Char('='))) {
-            return *it;
+    for (const QString &arg : args) {
+        if (!arg.contains(QLatin1Char('='))) {
+            return arg;
         }
     }
     return QString();
diff --git a/src/core/kcoredirlister.cpp b/src/core/kcoredirlister.cpp
--- a/src/core/kcoredirlister.cpp
+++ b/src/core/kcoredirlister.cpp
@@ -517,9 +517,8 @@
     lister->d->lstDirs.clear();
 
     qCDebug(KIO_CORE_DIRLISTER) << "Iterating over dirs" << lstDirsCopy;
-    for (QList<QUrl>::const_iterator it = lstDirsCopy.begin();
-            it != lstDirsCopy.end(); ++it) {
-        forgetDirs(lister, *it, false);
+    for (const QUrl &dir : lstDirsCopy) {
+        forgetDirs(lister, dir, false);
     }
 }
 
@@ -844,8 +843,7 @@
     QMap<QUrl, KFileItemList> removedItemsByDir;
     QList<QUrl> deletedSubdirs;
 
-    for (auto it = fileList.cbegin(), cend = fileList.end(); it != cend; ++it) {
-        QUrl url(*it);
+    for (const QUrl &url : fileList) {
         DirItem *dirItem = dirItemForUrl(url); // is it a listed directory?
         if (dirItem) {
             deletedSubdirs.append(url);
@@ -893,9 +891,8 @@
 {
     qCDebug(KIO_CORE_DIRLISTER) << fileList;
     QList<QUrl> dirsToUpdate;
-    QStringList::const_iterator it = fileList.begin();
-    for (; it != fileList.end(); ++it) {
-        QUrl url(*it);
+    for (const QString &fileUrl : fileList) {
+        const QUrl url(fileUrl);
         const KFileItem &fileitem = findByUrl(nullptr, url);
         if (fileitem.isNull()) {
             qCDebug(KIO_CORE_DIRLISTER) << "item not found for" << url;
@@ -914,9 +911,8 @@
         }
     }
 
-    QList<QUrl>::const_iterator itdir = dirsToUpdate.constBegin();
-    for (; itdir != dirsToUpdate.constEnd(); ++itdir) {
-        updateDirectory(*itdir);
+    for (const QUrl &dirUrl : qAsConst(dirsToUpdate)) {
+        updateDirectory(dirUrl);
     }
     // ## TODO problems with current jobs listing/updating that dir
     // ( see kde-2.2.2's kdirlister )
@@ -1574,8 +1570,8 @@
             // Rename all items under that dir
             // If all items of the directory change the same part of their url, the order is not
             // changed, therefore just change it in the list.
-            for (auto kit = dir->lstItems.begin(), kend = dir->lstItems.end(); kit != kend; ++kit) {
-                const KFileItem oldItem = *kit;
+            for (KFileItem &item : dir->lstItems) {
+                const KFileItem oldItem = item;
                 KFileItem newItem = oldItem;
                 const QUrl &oldItemUrl = oldItem.url();
                 QUrl newItemUrl(oldItemUrl);
@@ -1585,7 +1581,7 @@
 
                 listers |= emitRefreshItem(oldItem, newItem);
                 // Change the item
-                kit->setUrl(newItemUrl);
+                item.setUrl(newItemUrl);
             }
         }
     }
@@ -1751,8 +1747,8 @@
 
     // Fill the hash from the old list of items. We'll remove entries as we see them
     // in the new listing, and the resulting hash entries will be the deleted items.
-    for (auto kit = dir->lstItems.begin(), kend = dir->lstItems.end(); kit != kend; ++kit) {
-        fileItems.insert((*kit).name(), *kit);
+    for (const KFileItem &item : qAsConst(dir->lstItems)) {
+        fileItems.insert(item.name(), item);
     }
 
     QSet<QString> filesToHide;
@@ -2304,8 +2300,8 @@
     d->nameFilter = nameFilter;
     // Split on white space
     const QStringList list = nameFilter.split(QLatin1Char(' '), QString::SkipEmptyParts);
-    for (QStringList::const_iterator it = list.begin(); it != list.end(); ++it) {
-        d->settings.lstFilters.append(QRegExp(*it, Qt::CaseInsensitive, QRegExp::Wildcard));
+    for (const QString &filter : list) {
+        d->settings.lstFilters.append(QRegExp(filter, Qt::CaseInsensitive, QRegExp::Wildcard));
     }
 }
 
@@ -2394,10 +2390,11 @@
 
 bool KCoreDirLister::doNameFilter(const QString &name, const QList<QRegExp> &filters) const
 {
-    for (QList<QRegExp>::const_iterator it = filters.begin(); it != filters.end(); ++it)
-        if ((*it).exactMatch(name)) {
+    for (const QRegExp &filter : filters) {
+        if (filter.exactMatch(name)) {
             return true;
         }
+    }
 
     return false;
 }
diff --git a/src/core/kioglobal_p.cpp b/src/core/kioglobal_p.cpp
--- a/src/core/kioglobal_p.cpp
+++ b/src/core/kioglobal_p.cpp
@@ -38,13 +38,12 @@
             { QStandardPaths::DocumentsLocation, QStringLiteral("folder-documents") },
             { QStandardPaths::DesktopLocation, QStringLiteral("user-desktop") },
             { QStandardPaths::HomeLocation, QStringLiteral("user-home") } };
-    static const int count = sizeof mapping / sizeof *mapping;
 
     QMap<QString, QString> map;
-    for (int i = 0 ; i < count; ++i) {
-        const auto locations = QStandardPaths::standardLocations(mapping[i].location);
+    for (const auto &row : mapping) {
+        const QStringList locations = QStandardPaths::standardLocations(row.location);
         for (const QString &location : locations) {
-            map.insert(location, mapping[i].name);
+            map.insert(location, row.name);
         }
     }
     return map;
diff --git a/src/core/kmountpoint.cpp b/src/core/kmountpoint.cpp
--- a/src/core/kmountpoint.cpp
+++ b/src/core/kmountpoint.cpp
@@ -426,12 +426,12 @@
 
     int max = 0;
     KMountPoint::Ptr result;
-    for (const_iterator it = begin(); it != end(); ++it) {
-        const QString mountpoint = (*it)->d->mountPoint;
+    for (const KMountPoint::Ptr &mp : *this) {
+        const QString mountpoint = mp->d->mountPoint;
         const int length = mountpoint.length();
         if (length > max && pathsAreParentAndChildOrEqual(mountpoint, realname)) {
             max = length;
-            result = *it;
+            result = mp;
             // keep iterating to check for a better match (bigger max)
         }
     }
@@ -444,10 +444,10 @@
     if (realDevice.isEmpty()) { // d->device can be empty in the loop below, don't match empty with it
         return Ptr();
     }
-    for (const_iterator it = begin(); it != end(); ++it) {
-        if (realDevice.compare((*it)->d->device, cs) == 0 ||
-                realDevice.compare((*it)->d->mountedFrom, cs) == 0) {
-            return *it;
+    for (const KMountPoint::Ptr &mountPoint : *this) {
+        if (realDevice.compare(mountPoint->d->device, cs) == 0 ||
+                realDevice.compare(mountPoint->d->mountedFrom, cs) == 0) {
+            return mountPoint;
         }
     }
     return Ptr();
diff --git a/src/core/kprotocolmanager.cpp b/src/core/kprotocolmanager.cpp
--- a/src/core/kprotocolmanager.cpp
+++ b/src/core/kprotocolmanager.cpp
@@ -1305,11 +1305,10 @@
     QMutexLocker lock(&d->mutex);
     if (d->protocolForArchiveMimetypes.isEmpty()) {
         const QList<KProtocolInfoPrivate *> allProtocols = KProtocolInfoFactory::self()->allProtocols();
-        for (QList<KProtocolInfoPrivate *>::const_iterator it = allProtocols.begin();
-                it != allProtocols.end(); ++it) {
-            const QStringList archiveMimetypes = (*it)->m_archiveMimeTypes;
+        for (KProtocolInfoPrivate *allProtocol : allProtocols) {
+            const QStringList archiveMimetypes = allProtocol->m_archiveMimeTypes;
             for (const QString &mime : archiveMimetypes) {
-                d->protocolForArchiveMimetypes.insert(mime, (*it)->m_name);
+                d->protocolForArchiveMimetypes.insert(mime, allProtocol->m_name);
             }
         }
     }
diff --git a/src/core/krecentdocument.cpp b/src/core/krecentdocument.cpp
--- a/src/core/krecentdocument.cpp
+++ b/src/core/krecentdocument.cpp
@@ -63,14 +63,13 @@
     const QStringList list = d.entryList();
     QStringList fullList;
 
-    for (QStringList::ConstIterator it = list.begin(); it != list.end(); ++it) {
-        QString fileName = *it;
+    for (const QString &fileName : list) {
         QString pathDesktop;
         if (fileName.startsWith(QLatin1Char(':'))) {
             // See: https://bugreports.qt.io/browse/QTBUG-11223
-            pathDesktop = KRecentDocument::recentDocumentDirectory() + *it;
+            pathDesktop = KRecentDocument::recentDocumentDirectory() + fileName;
         } else {
-            pathDesktop = d.absoluteFilePath(*it);
+            pathDesktop = d.absoluteFilePath(fileName);
         }
         KDesktopFile tmpDesktopFile(pathDesktop);
         QUrl urlDesktopFile(tmpDesktopFile.desktopGroup().readPathEntry("URL", QString()));
@@ -168,8 +167,8 @@
 {
     const QStringList list = recentDocuments();
     QDir dir;
-    for (QStringList::ConstIterator it = list.begin(); it != list.end(); ++it) {
-        dir.remove(*it);
+    for (const QString &desktopFilePath : list) {
+        dir.remove(desktopFilePath);
     }
 }
 
diff --git a/src/core/ksambashare.cpp b/src/core/ksambashare.cpp
--- a/src/core/ksambashare.cpp
+++ b/src/core/ksambashare.cpp
@@ -50,8 +50,6 @@
     "/usr/lib/smb.conf",
     "/usr/local/lib/smb.conf"
 };
-static const int DefaultSambaConfigFilePathListSize = sizeof(DefaultSambaConfigFilePathList)
-        / sizeof(char *);
 
 KSambaSharePrivate::KSambaSharePrivate(KSambaShare *parent)
     : q_ptr(parent)
@@ -85,8 +83,8 @@
 // in several well-known paths
 bool KSambaSharePrivate::findSmbConf()
 {
-    for (int i = 0; i < DefaultSambaConfigFilePathListSize; ++i) {
-        const QString filePath = QString::fromLatin1(DefaultSambaConfigFilePathList[i]);
+    for (const char *str : DefaultSambaConfigFilePathList) {
+        const QString filePath = QString::fromLatin1(str);
         if (QFile::exists(filePath)) {
             smbConf = filePath;
             return true;
diff --git a/src/core/ksslcertificatemanager.cpp b/src/core/ksslcertificatemanager.cpp
--- a/src/core/ksslcertificatemanager.cpp
+++ b/src/core/ksslcertificatemanager.cpp
@@ -381,9 +381,9 @@
 
     KConfig config(QStringLiteral("ksslcablacklist"), KConfig::SimpleConfig);
     KConfigGroup group = config.group("Blacklist of CA Certificates");
-    for (int i = 0; i < ret.size(); i++) {
-        if (group.hasKey(ret[i].certHash.constData())) {
-            ret[i].isBlacklisted = true;
+    for (KSslCaCertificate &cert : ret) {
+        if (group.hasKey(cert.certHash.constData())) {
+            cert.isBlacklisted = true;
             //qDebug() << "is blacklisted";
         }
     }
diff --git a/src/core/udsentry.cpp b/src/core/udsentry.cpp
--- a/src/core/udsentry.cpp
+++ b/src/core/udsentry.cpp
@@ -150,8 +150,8 @@
 {
     QList<uint> res;
     res.reserve(storage.size());
-    for (auto it = storage.cbegin(), end = storage.cend(); it != end; ++it) {
-        res.append(it->m_index);
+    for (const Field &field : storage) {
+        res.append(field.m_index);
     }
     return res;
 }
@@ -161,8 +161,8 @@
 {
     QVector<uint> res;
     res.reserve(storage.size());
-    for (auto it = storage.cbegin(), end = storage.cend(); it != end; ++it) {
-        res.append(it->m_index);
+    for (const Field &field : storage) {
+        res.append(field.m_index);
     }
     return res;
 }
@@ -183,15 +183,14 @@
 {
     s << static_cast<quint32>(storage.size());
 
-    for (auto it = storage.cbegin(), end = storage.cend(); it != end; ++it)
-    {
-        uint uds = it->m_index;
+    for (const Field &field : storage) {
+        uint uds = field.m_index;
         s << uds;
 
         if (uds & KIO::UDSEntry::UDS_STRING) {
-            s << it->m_str;
+            s << field.m_str;
         } else if (uds & KIO::UDSEntry::UDS_NUMBER) {
-            s << it->m_long;
+            s << field.m_long;
         } else {
             Q_ASSERT_X(false, "KIO::UDSEntry", "Found a field with an invalid type");
         }
@@ -312,12 +311,12 @@
 {
     QDebugStateSaver saver(stream);
     stream.nospace() << "[";
-    for (auto it = storage.cbegin(), end = storage.cend(); it != end; ++it) {
-        stream << " " << nameOfUdsField(it->m_index) << "=";
-        if (it->m_index & KIO::UDSEntry::UDS_STRING) {
-            stream << it->m_str;
-        } else if (it->m_index & KIO::UDSEntry::UDS_NUMBER) {
-            stream << it->m_long;
+    for (const Field &field : storage) {
+        stream << " " << nameOfUdsField(field.m_index) << "=";
+        if (field.m_index & KIO::UDSEntry::UDS_STRING) {
+            stream << field.m_str;
+        } else if (field.m_index & KIO::UDSEntry::UDS_NUMBER) {
+            stream << field.m_long;
         } else {
             Q_ASSERT_X(false, "KIO::UDSEntry", "Found a field with an invalid type");
         }
diff --git a/src/filewidgets/kdirsortfilterproxymodel.cpp b/src/filewidgets/kdirsortfilterproxymodel.cpp
--- a/src/filewidgets/kdirsortfilterproxymodel.cpp
+++ b/src/filewidgets/kdirsortfilterproxymodel.cpp
@@ -116,19 +116,19 @@
 {
     int points = 0;
 
-    QFile::Permission permissionsCheck[] = { QFile::ReadUser,
-                                             QFile::WriteUser,
-                                             QFile::ExeUser,
-                                             QFile::ReadGroup,
-                                             QFile::WriteGroup,
-                                             QFile::ExeGroup,
-                                             QFile::ReadOther,
-                                             QFile::WriteOther,
-                                             QFile::ExeOther
-                                           };
-
-    for (int i = 0; i < 9; i++) {
-        points += info.permission(permissionsCheck[i]) ? 1 : 0;
+    const QFile::Permission permissionsCheck[] = { QFile::ReadUser,
+                                                   QFile::WriteUser,
+                                                   QFile::ExeUser,
+                                                   QFile::ReadGroup,
+                                                   QFile::WriteGroup,
+                                                   QFile::ExeGroup,
+                                                   QFile::ReadOther,
+                                                   QFile::WriteOther,
+                                                   QFile::ExeOther
+                                                 };
+
+    for (QFile::Permission perm : permissionsCheck) {
+        points += info.permission(perm) ? 1 : 0;
     }
 
     return points;
diff --git a/src/ioslaves/help/kio_help.cpp b/src/ioslaves/help/kio_help.cpp
--- a/src/ioslaves/help/kio_help.cpp
+++ b/src/ioslaves/help/kio_help.cpp
@@ -56,18 +56,18 @@
 
     // this is kind of compat hack as we install our docs in en/ but the
     // default language is en_US
-    for (QStringList::Iterator it = langs.begin(); it != langs.end(); ++it)
-        if (*it == QLatin1String("en_US")) {
-            *it = QStringLiteral("en");
+    for (QString &lang : langs) {
+        if (lang == QLatin1String("en_US")) {
+            lang = QStringLiteral("en");
         }
+    }
 
     // look up the different languages
     int ldCount = localDoc.count();
     search.reserve(ldCount * langs.size());
     for (int id = 0; id < ldCount; id++) {
-        QStringList::ConstIterator lang;
-        for (lang = langs.constBegin(); lang != langs.constEnd(); ++lang) {
-            search.append(QStringLiteral("%1/%2/%3").arg(localDoc[id], *lang, fname));
+        for (const QString &lang : qAsConst(langs)) {
+            search.append(QStringLiteral("%1/%2/%3").arg(localDoc[id], lang, fname));
         }
     }
 
diff --git a/src/ioslaves/http/http.cpp b/src/ioslaves/http/http.cpp
--- a/src/ioslaves/http/http.cpp
+++ b/src/ioslaves/http/http.cpp
@@ -166,17 +166,17 @@
     QString sanitizedHeaders;
     const QStringList headers = _header.split(QRegExp(QStringLiteral("[\r\n]")));
 
-    for (QStringList::ConstIterator it = headers.begin(); it != headers.end(); ++it) {
+    for (const QString &header : headers) {
         // Do not allow Request line to be specified and ignore
         // the other HTTP headers.
-        if (!(*it).contains(QLatin1Char(':')) ||
-                (*it).startsWith(QLatin1String("host"), Qt::CaseInsensitive) ||
-                (*it).startsWith(QLatin1String("proxy-authorization"), Qt::CaseInsensitive) ||
-                (*it).startsWith(QLatin1String("via"), Qt::CaseInsensitive)) {
+        if (!header.contains(QLatin1Char(':')) ||
+                header.startsWith(QLatin1String("host"), Qt::CaseInsensitive) ||
+                header.startsWith(QLatin1String("proxy-authorization"), Qt::CaseInsensitive) ||
+                header.startsWith(QLatin1String("via"), Qt::CaseInsensitive)) {
             continue;
         }
 
-        sanitizedHeaders += (*it) + QLatin1String("\r\n");
+        sanitizedHeaders += header + QLatin1String("\r\n");
     }
     sanitizedHeaders.chop(2);
 
diff --git a/src/ioslaves/trash/kio_trash.cpp b/src/ioslaves/trash/kio_trash.cpp
--- a/src/ioslaves/trash/kio_trash.cpp
+++ b/src/ioslaves/trash/kio_trash.cpp
@@ -418,9 +418,7 @@
     const QStringList entryNames = impl.listDir(info.physicalPath);
     totalSize(entryNames.count());
     KIO::UDSEntry entry;
-    for (QStringList::const_iterator entryIt = entryNames.begin(), entryEnd = entryNames.end();
-            entryIt != entryEnd; ++entryIt) {
-        const QString fileName = *entryIt;
+    for (const QString &fileName : entryNames) {
         if (fileName == QLatin1String("..")) {
             continue;
         }
@@ -502,12 +500,12 @@
     KIO::UDSEntry entry;
     createTopLevelDirEntry(entry);
     listEntry(entry);
-    for (TrashedFileInfoList::ConstIterator it = lst.begin(); it != lst.end(); ++it) {
-        const QUrl url = TrashImpl::makeURL((*it).trashId, (*it).fileId, QString());
+    for (const TrashedFileInfo &fileInfo : lst) {
+        const QUrl url = TrashImpl::makeURL(fileInfo.trashId, fileInfo.fileId, QString());
         entry.clear();
-        const QString fileDisplayName = (*it).fileId;
+        const QString fileDisplayName = fileInfo.fileId;
 
-        if (createUDSEntry((*it).physicalPath, fileDisplayName, url.fileName(), entry, *it)) {
+        if (createUDSEntry(fileInfo.physicalPath, fileDisplayName, url.fileName(), entry, fileInfo)) {
             listEntry(entry);
         }
     }
diff --git a/src/ioslaves/trash/tests/testtrash.cpp b/src/ioslaves/trash/tests/testtrash.cpp
--- a/src/ioslaves/trash/tests/testtrash.cpp
+++ b/src/ioslaves/trash/tests/testtrash.cpp
@@ -1245,8 +1245,7 @@
 
 void TestTrash::slotEntries(KIO::Job *, const KIO::UDSEntryList &lst)
 {
-    for (KIO::UDSEntryList::ConstIterator it = lst.begin(); it != lst.end(); ++it) {
-        const KIO::UDSEntry &entry(*it);
+    for (const KIO::UDSEntry &entry : lst) {
         QString name = entry.stringValue(KIO::UDSEntry::UDS_NAME);
         QString displayName = entry.stringValue(KIO::UDSEntry::UDS_DISPLAY_NAME);
         QUrl url(entry.stringValue(KIO::UDSEntry::UDS_URL));
diff --git a/src/ioslaves/trash/trashimpl.cpp b/src/ioslaves/trash/trashimpl.cpp
--- a/src/ioslaves/trash/trashimpl.cpp
+++ b/src/ioslaves/trash/trashimpl.cpp
@@ -221,9 +221,7 @@
 
     const QStringList entries = listDir(oldTrashDir);
     bool allOK = true;
-    for (QStringList::const_iterator entryIt = entries.begin(), entryEnd = entries.end();
-            entryIt != entryEnd; ++entryIt) {
-        QString srcPath = *entryIt;
+    for (QString srcPath : entries) {
         if (srcPath == QLatin1Char('.') || srcPath == QLatin1String("..") || srcPath == QLatin1String(".directory")) {
             continue;
         }
@@ -1092,8 +1090,8 @@
 #endif
 
     const QList<Solid::Device> lst = Solid::Device::listFromQuery(QStringLiteral("StorageAccess.accessible == true"));
-    for (QList<Solid::Device>::ConstIterator it = lst.begin(); it != lst.end(); ++it) {
-        QString topdir = (*it).as<Solid::StorageAccess>()->filePath();
+    for (const Solid::Device &device : lst) {
+        QString topdir = device.as<Solid::StorageAccess>()->filePath();
         QString trashDir = trashForMountPoint(topdir, false);
         if (!trashDir.isEmpty()) {
             // OK, trashDir is a valid trash directory. Ensure it's registered.
@@ -1103,7 +1101,7 @@
 #ifdef Q_OS_OSX
                 trashId = idForMountPoint(topdir);
 #else
-                trashId = idForDevice(*it);
+                trashId = idForDevice(device);
 #endif
                 if (trashId == -1) {
                     continue;
diff --git a/src/kcms/kio/smbrodlg.cpp b/src/kcms/kio/smbrodlg.cpp
--- a/src/kcms/kio/smbrodlg.cpp
+++ b/src/kcms/kio/smbrodlg.cpp
@@ -144,9 +144,7 @@
    //least better than storing the plain password
    QString password(m_passwordLe->text());
    QString scrambled;
-   for (int i=0; i<password.length(); i++)
-   {
-      QChar c = password[i];
+   for (const QChar c : qAsConst(password)) {
       unsigned int num = (c.unicode() ^ 173) + 17;
       unsigned int a1 = (num & 0xFC00) >> 10;
       unsigned int a2 = (num & 0x3E0) >> 5;
diff --git a/src/kntlm/kntlm.cpp b/src/kntlm/kntlm.cpp
--- a/src/kntlm/kntlm.cpp
+++ b/src/kntlm/kntlm.cpp
@@ -130,14 +130,13 @@
     key[6] = ((key_56[5] << 2) & 0xFF) | (key_56[6] >> 6);
     key[7] = (key_56[6] << 1) & 0xFF;
 
-    for (uint i = 0; i < 8; i++) {
-        unsigned char b = key[i];
-        bool needsParity = ((((b >> 7) ^ (b >> 6) ^ (b >> 5) ^ (b >> 4) ^ (b >> 3) ^ (b >> 2) ^ (b >> 1)) & 0x01) == 0);
+    for (unsigned char &b : key) {
+        const bool needsParity = ((((b >> 7) ^ (b >> 6) ^ (b >> 5) ^ (b >> 4) ^ (b >> 3) ^ (b >> 2) ^ (b >> 1)) & 0x01) == 0);
 
         if (needsParity) {
-            key[i] |= 0x01;
+            b |= 0x01;
         } else {
-            key[i] &= 0xfe;
+            b &= 0xfe;
         }
     }
 
@@ -156,8 +155,8 @@
     now *= (quint64) 10000000;
     bl->timestamp = qToLittleEndian(now);
 
-    for (uint i = 0; i < 8; i++) {
-        bl->challenge[i] = KRandom::random() % 0xff;
+    for (unsigned char &b : bl->challenge) {
+        b = KRandom::random() % 0xff;
     }
 
     memcpy(blob.data() + NTLM_BLOB_SIZE, targetinfo.data(), targetinfo.size());
diff --git a/src/kpac/proxyscout.cpp b/src/kpac/proxyscout.cpp
--- a/src/kpac/proxyscout.cpp
+++ b/src/kpac/proxyscout.cpp
@@ -253,18 +253,18 @@
     }
 
     if (success) {
-        for (RequestQueue::Iterator it = m_requestQueue.begin(), itEnd = m_requestQueue.end(); it != itEnd; ++it) {
-            if ((*it).sendAll) {
-                const QVariant result(handleRequest((*it).url));
-                QDBusConnection::sessionBus().send((*it).transaction.createReply(result));
+        for (const QueuedRequest &request : qAsConst(m_requestQueue)) {
+            if (request.sendAll) {
+                const QVariant result(handleRequest(request.url));
+                QDBusConnection::sessionBus().send(request.transaction.createReply(result));
             } else {
-                const QVariant result(handleRequest((*it).url).constFirst());
-                QDBusConnection::sessionBus().send((*it).transaction.createReply(result));
+                const QVariant result(handleRequest(request.url).constFirst());
+                QDBusConnection::sessionBus().send(request.transaction.createReply(result));
             }
         }
     } else {
-        for (RequestQueue::Iterator it = m_requestQueue.begin(), itEnd = m_requestQueue.end(); it != itEnd; ++it) {
-            QDBusConnection::sessionBus().send((*it).transaction.createReply(QLatin1String("DIRECT")));
+        for (const QueuedRequest &request : qAsConst(m_requestQueue)) {
+            QDBusConnection::sessionBus().send(request.transaction.createReply(QLatin1String("DIRECT")));
         }
     }
 
diff --git a/src/kssld/kssld.cpp b/src/kssld/kssld.cpp
--- a/src/kssld/kssld.cpp
+++ b/src/kssld/kssld.cpp
@@ -61,11 +61,10 @@
             {"HostNameMismatch", KSslError::HostNameMismatch}
         };
 
-        for (int i = 0; i < int(sizeof(strError) / sizeof(strErr)); i++) {
-            QString s = QString::fromLatin1(strError[i].str);
-            KSslError::Error e = strError[i].err;
-            stringToSslError.insert(s, e);
-            sslErrorToString.insert(e, s);
+        for (const strErr &row : strError) {
+            QString s = QString::fromLatin1(row.str);
+            stringToSslError.insert(s, row.err);
+            sslErrorToString.insert(row.err, s);
         }
     }
 
diff --git a/src/widgets/kfileitemdelegate.cpp b/src/widgets/kfileitemdelegate.cpp
--- a/src/widgets/kfileitemdelegate.cpp
+++ b/src/widgets/kfileitemdelegate.cpp
@@ -315,13 +315,7 @@
 QString KFileItemDelegate::Private::replaceNewlines(const QString &text) const
 {
     QString string = text;
-    const QChar newline = QLatin1Char('\n');
-
-    for (int i = 0; i < string.length(); i++)
-        if (string[i] == newline) {
-            string[i] = QChar::LineSeparator;
-        }
-
+    string.replace(QLatin1Char('\n'), QChar::LineSeparator);
     return string;
 }
 
diff --git a/src/widgets/kopenwithdialog.cpp b/src/widgets/kopenwithdialog.cpp
--- a/src/widgets/kopenwithdialog.cpp
+++ b/src/widgets/kopenwithdialog.cpp
@@ -144,14 +144,12 @@
 
     const KServiceGroup::List list = root->entries();
 
-    for (KServiceGroup::List::ConstIterator it = list.begin();
-            it != list.end(); ++it) {
+    for (const KSycocaEntry::Ptr &p : list) {
         QString icon;
         QString text;
         QString entryPath;
         QString exec;
         bool isDir = false;
-        const KSycocaEntry::Ptr p = (*it);
         if (p->isType(KST_KService)) {
             const KService::Ptr service(static_cast<KService*>(p.data()));
 
diff --git a/src/widgets/kpropertiesdialog.cpp b/src/widgets/kpropertiesdialog.cpp
--- a/src/widgets/kpropertiesdialog.cpp
+++ b/src/widgets/kpropertiesdialog.cpp
@@ -3185,9 +3185,7 @@
     QStringList devices;
     const KMountPoint::List mountPoints = KMountPoint::possibleMountPoints();
 
-    for (KMountPoint::List::ConstIterator it = mountPoints.begin();
-            it != mountPoints.end(); ++it) {
-        const KMountPoint::Ptr mp = (*it);
+    for (const KMountPoint::Ptr &mp : mountPoints) {
         QString mountPoint = mp->mountPoint();
         QString device = mp->mountedFrom();
         // qDebug()<<"mountPoint :"<<mountPoint<<" device :"<<device<<" mp->mountType() :"<<mp->mountType();
diff --git a/src/widgets/krun.cpp b/src/widgets/krun.cpp
--- a/src/widgets/krun.cpp
+++ b/src/widgets/krun.cpp
@@ -586,20 +586,19 @@
 {
     // Check which protocols the application supports.
     // This can be a list of actual protocol names, or just KIO for KDE apps.
-    QStringList appSupportedProtocols = KIO::DesktopExecParser::supportedProtocols(_service);
+    const QStringList appSupportedProtocols = KIO::DesktopExecParser::supportedProtocols(_service);
     QList<QUrl> urls(_urls);
     if (!appSupportedProtocols.contains(QLatin1String("KIO"))) {
-        for (QList<QUrl>::Iterator it = urls.begin(); it != urls.end(); ++it) {
-            const QUrl url = *it;
+        for (QUrl &url : urls) {
             bool supported = KIO::DesktopExecParser::isProtocolInSupportedList(url, appSupportedProtocols);
             //qDebug() << "Looking at url=" << url << " supported=" << supported;
             if (!supported && KProtocolInfo::protocolClass(url.scheme()) == QLatin1String(":local")) {
                 // Maybe we can resolve to a local URL?
                 KIO::StatJob *job = KIO::mostLocalUrl(url);
                 if (job->exec()) { // ## nasty nested event loop!
                     const QUrl localURL = job->mostLocalUrl();
                     if (localURL != url) {
-                        *it = localURL;
+                        url = localURL;
                         //qDebug() << "Changed to" << localURL;
                     }
                 }
diff --git a/src/widgets/kshellcompletion.cpp b/src/widgets/kshellcompletion.cpp
--- a/src/widgets/kshellcompletion.cpp
+++ b/src/widgets/kshellcompletion.cpp
@@ -79,8 +79,8 @@
     //
     bool is_exe_completion = true;
 
-    for (int i = 0; i < d->m_text_start.length(); i++) {
-        if (d->m_text_start[i] != d->m_word_break_char) {
+    for (const QChar ch : qAsConst(d->m_text_start)) {
+        if (ch != d->m_word_break_char) {
             is_exe_completion = false;
             break;
         }
@@ -124,34 +124,33 @@
 {
     KUrlCompletion::postProcessMatches(matches);
 
-    for (QStringList::Iterator it = matches->begin();
-            it != matches->end(); ++it) {
-        if (!(*it).isNull()) {
-            if ((*it).endsWith(QLatin1Char('/'))) {
-                d->quoteText(&(*it), false, true);    // don't quote trailing '/'
+    for (QString &match : *matches) {
+        if (!match.isNull()) {
+            if (match.endsWith(QLatin1Char('/'))) {
+                d->quoteText(&match, false, true);    // don't quote trailing '/'
             } else {
-                d->quoteText(&(*it), false, false);    // quote the whole text
+                d->quoteText(&match, false, false);    // quote the whole text
             }
 
-            (*it).prepend(d->m_text_start);
+            match.prepend(d->m_text_start);
         }
     }
 }
 
 void KShellCompletion::postProcessMatches(KCompletionMatches *matches) const
 {
     KUrlCompletion::postProcessMatches(matches);
 
-    for (KCompletionMatches::Iterator it = matches->begin();
-            it != matches->end(); ++it) {
-        if (!(*it).value().isNull()) {
-            if ((*it).value().endsWith(QLatin1Char('/'))) {
-                d->quoteText(&(*it).value(), false, true);    // don't quote trailing '/'
+    for (auto &match : *matches) {
+        QString& matchString = match.value();
+        if (!matchString.isNull()) {
+            if (matchString.endsWith(QLatin1Char('/'))) {
+                d->quoteText(&matchString, false, true);    // don't quote trailing '/'
             } else {
-                d->quoteText(&(*it).value(), false, false);    // quote the whole text
+                d->quoteText(&matchString, false, false);    // quote the whole text
             }
 
-            (*it).value().prepend(d->m_text_start);
+            matchString.prepend(d->m_text_start);
         }
     }
 }
@@ -291,24 +290,24 @@
     QChar p_last_quote_char;
     QString result;
 
-    for (int pos = 0; pos < text.length(); pos++) {
+    for (const QChar ch : text) {
 
         if (escaped) {
             escaped = false;
-            result.insert(result.length(), text[pos]);
-        } else if (in_quote && text[pos] == p_last_quote_char) {
+            result.insert(result.length(), ch);
+        } else if (in_quote && ch == p_last_quote_char) {
             in_quote = false;
-        } else if (!in_quote && text[pos] == m_quote_char1) {
+        } else if (!in_quote && ch == m_quote_char1) {
             p_last_quote_char = m_quote_char1;
             in_quote = true;
-        } else if (!in_quote && text[pos] == m_quote_char2) {
+        } else if (!in_quote && ch == m_quote_char2) {
             p_last_quote_char = m_quote_char2;
             in_quote = true;
-        } else if (text[pos] == m_escape_char) {
+        } else if (ch == m_escape_char) {
             escaped = true;
-            result.insert(result.length(), text[pos]);
+            result.insert(result.length(), ch);
         } else {
-            result.insert(result.length(), text[pos]);
+            result.insert(result.length(), ch);
         }
 
     }
diff --git a/src/widgets/ksslinfodialog.cpp b/src/widgets/ksslinfodialog.cpp
--- a/src/widgets/ksslinfodialog.cpp
+++ b/src/widgets/ksslinfodialog.cpp
@@ -147,8 +147,7 @@
     d->certificateErrors = validationErrors;
 
     d->ui.certSelector->clear();
-    for (int i = 0; i < certificateChain.size(); i++) {
-        const QSslCertificate &cert = certificateChain[i];
+    for (const QSslCertificate &cert : certificateChain) {
         QString name;
         static const QSslCertificate::SubjectInfo si[] = {
             QSslCertificate::CommonName,
diff --git a/src/widgets/kurlcompletion.cpp b/src/widgets/kurlcompletion.cpp
--- a/src/widgets/kurlcompletion.cpp
+++ b/src/widgets/kurlcompletion.cpp
@@ -1545,11 +1545,13 @@
 static QString unescape(const QString &text)
 {
     QString result;
+    result.reserve(text.size());
 
-    for (int pos = 0; pos < text.length(); pos++)
-        if (text.at(pos) != QLatin1Char('\\')) {
-            result.insert(result.length(), text.at(pos));
+    for (const QChar ch : text) {
+        if (ch != QLatin1Char('\\')) {
+            result.append(ch);
         }
+    }
 
     return result;
 }
diff --git a/src/widgets/kurlrequester.cpp b/src/widgets/kurlrequester.cpp
--- a/src/widgets/kurlrequester.cpp
+++ b/src/widgets/kurlrequester.cpp
@@ -235,11 +235,11 @@
     {
         QStringList qFilters = filters.split(QLatin1Char('\n'), QString::SkipEmptyParts);
 
-        for (QStringList::iterator it = qFilters.begin(); it != qFilters.end(); ++it) {
-            int sep = it->indexOf(QLatin1Char('|'));
-            const QStringRef globs = it->leftRef(sep);
-            const QStringRef desc  = it->midRef(sep + 1);
-            *it = desc + QLatin1String(" (") + globs + QLatin1Char(')');
+        for (QString &qFilter : qFilters) {
+            int sep = qFilter.indexOf(QLatin1Char('|'));
+            const QStringRef globs = qFilter.leftRef(sep);
+            const QStringRef desc  = qFilter.midRef(sep + 1);
+            qFilter = desc + QLatin1String(" (") + globs + QLatin1Char(')');
         }
 
         return qFilters;
diff --git a/src/widgets/previewjob.cpp b/src/widgets/previewjob.cpp
--- a/src/widgets/previewjob.cpp
+++ b/src/widgets/previewjob.cpp
@@ -756,10 +756,12 @@
 {
     QStringList result;
     const KService::List plugins = KServiceTypeTrader::self()->query(QStringLiteral("ThumbCreator"));
-    for (KService::List::ConstIterator it = plugins.begin(); it != plugins.end(); ++it)
-        if (!result.contains((*it)->desktopEntryName())) {
-            result.append((*it)->desktopEntryName());
+    for (const KService::Ptr &plugin : plugins) {
+        const QString desktopEntryName = plugin->desktopEntryName();
+        if (!result.contains(desktopEntryName)) {
+            result.append(desktopEntryName);
         }
+    }
     return result;
 }
 
@@ -780,8 +782,8 @@
 {
     QStringList result;
     const KService::List plugins = KServiceTypeTrader::self()->query(QStringLiteral("ThumbCreator"));
-    for (KService::List::ConstIterator it = plugins.begin(); it != plugins.end(); ++it) {
-        result += (*it)->mimeTypes();
+    for (const KService::Ptr &plugin : plugins) {
+        result += plugin->mimeTypes();
     }
     return result;
 }
@@ -801,9 +803,9 @@
 {
     KFileItemList fileItems;
     fileItems.reserve(items.size());
-    for (QList<QUrl>::const_iterator it = items.begin(); it != items.end(); ++it) {
-        Q_ASSERT((*it).isValid());   // please call us with valid urls only
-        fileItems.append(KFileItem(*it));
+    for (const QUrl &url : items) {
+        Q_ASSERT(url.isValid());   // please call us with valid urls only
+        fileItems.append(KFileItem(url));
     }
     return new PreviewJob(fileItems, width, height, iconSize, iconAlpha,
                           scale, save, enabledPlugins);