--- a/libgui/src/dialog.cc	Wed Apr 12 11:21:28 2023 +0200
+++ b/libgui/src/dialog.cc	Wed Apr 12 12:02:25 2023 +0200
@@ -39,6 +39,7 @@
 #include <QLabel>
 #include <QMessageBox>
 #include <QPushButton>
+#include <QRegularExpression>
 #include <QVBoxLayout>
 
 #include "dialog.h"
@@ -67,7 +68,7 @@
 QString QUIWidgetCreator::rm_amp (const QString& text)
 {
   QString text_wo_amp = text;
-  text_wo_amp.replace (QRegExp ("&(\\w)"), "\\1");
+  text_wo_amp.replace (QRegularExpression {"&(\\w)"}, "\\1");
   return text_wo_amp;
 }
 

--- a/libgui/src/documentation.cc	Wed Apr 12 11:21:28 2023 +0200
+++ b/libgui/src/documentation.cc	Wed Apr 12 12:02:25 2023 +0200
@@ -47,6 +47,7 @@
 #include <QLabel>
 #include <QLineEdit>
 #include <QMessageBox>
+#include <QRegularExpression>
 #include <QTabWidget>
 #include <QTimer>
 #include <QWheelEvent>
@@ -461,9 +462,10 @@
     return;
 
   // Get quoted search strings first, then take first string as fall back
-  QRegExp rx ("\"([^\"]*)\"");
-  if (rx.indexIn (query_string, 0) != -1)
-    m_internal_search = rx.cap (1);
+  QRegularExpression rx {"\"([^\"]*)\""};
+  QRegularExpressionMatch match = rx.match (query_string);
+  if (match.hasMatch ())
+    m_internal_search = match.captured (1);
   else
 #if defined (HAVE_QT_SPLITBEHAVIOR_ENUM)
     m_internal_search = query_string.split (" ", Qt::SkipEmptyParts).first ();
@@ -954,7 +956,7 @@
   QString retval = title;
   QString u = url.toString ();
 
-  retval.remove (QRegExp ("\\s*\\(*GNU Octave \\(version [^\\)]*\\)[: \\)]*"));
+  retval.remove (QRegularExpression {"\\s*\\(*GNU Octave \\(version [^\\)]*\\)[: \\)]*"});
 
   // Since the title only contains the section name and not the
   // specific anchor, extract the latter from the url and append
@@ -964,19 +966,22 @@
       // Get the anchor from the url
       QString anchor = u.split ('#').last ();
       // Remove internal string parts
-      anchor.remove (QRegExp ("^index-"));
-      anchor.remove (QRegExp ("^SEC_"));
-      anchor.remove (QRegExp ("^XREF"));
+      anchor.remove (QRegularExpression {"^index-"});
+      anchor.remove (QRegularExpression {"^SEC_"});
+      anchor.remove (QRegularExpression {"^XREF"});
       anchor.remove ("Concept-Index_cp_letter-");
       anchor.replace ("-", " ");
 
       // replace encoded special chars by their unencoded versions
-      QRegExp rx = QRegExp ("_00([0-7][0-9a-f])");
+      QRegularExpression rx {"_00([0-7][0-9a-f])"};
+      QRegularExpressionMatch match = rx.match (anchor, 0);
       int pos = 0;
-      while ((pos = rx.indexIn(anchor, pos)) != -1)
+      while (match.hasMatch ())
         {
-          anchor.replace ("_00"+rx.cap (1), QChar (rx.cap (1).toInt (nullptr, 16)));
-          pos += rx.matchedLength();
+          anchor.replace ("_00" + match.captured (1),
+                          QChar (match.captured (1).toInt (nullptr, 16)));
+          pos += match.capturedLength ();
+          match = rx.match (anchor, pos);
         }
 
       if (retval != anchor)

--- a/libgui/src/external-editor-interface.cc	Wed Apr 12 11:21:28 2023 +0200
+++ b/libgui/src/external-editor-interface.cc	Wed Apr 12 12:02:25 2023 +0200
@@ -29,6 +29,7 @@
 
 #include <QMessageBox>
 #include <QProcess>
+#include <QRegularExpression>
 
 #include "external-editor-interface.h"
 #include "gui-settings.h"
@@ -55,7 +56,7 @@
   editor.replace ("%f", file);
   editor.replace ("%l", QString::number (line));
 
-  QStringList arguments = editor.split (QRegExp("\\s+"));
+  QStringList arguments = editor.split (QRegularExpression {"\\s+"});
   editor = arguments.takeFirst ();
 
   // start the process and check for success

--- a/libgui/src/qt-interpreter-events.cc	Wed Apr 12 11:21:28 2023 +0200
+++ b/libgui/src/qt-interpreter-events.cc	Wed Apr 12 12:02:25 2023 +0200
@@ -35,6 +35,7 @@
 #include <QIcon>
 #include <QMetaType>
 #include <QPushButton>
+#include <QRegularExpression>
 #include <QStringList>
 
 #include "dialog.h"
@@ -93,7 +94,7 @@
 
       // Strip out extensions from name and replace ';' with spaces in list.
 
-      name.replace (QRegExp (R"(\(.*\))"), "");
+      name.replace (QRegularExpression {R"(\(.*\))"}, "");
       ext.replace (";", " ");
 
       if (name.isEmpty ())
@@ -728,19 +729,20 @@
       QStringList codecs;
       settings.get_codecs (&codecs);
 
-      QRegExp re ("^CP(\\d+)$");
+      QRegularExpression re {"^CP(\\d+)$"};
+      QRegularExpressionMatch match = re.match (adjusted_value);
 
       if (adjusted_value == "SYSTEM")
         adjusted_value =
           QString ("SYSTEM (") +
           QString (octave_locale_charset_wrapper ()).toUpper () +
           QString (")");
-      else if (re.indexIn (adjusted_value) > -1)
+      else if (match.hasMatch ())
         {
-          if (codecs.contains ("IBM" + re.cap (1)))
-            adjusted_value = "IBM" + re.cap (1);
-          else if (codecs.contains ("WINDOWS-" + re.cap (1)))
-            adjusted_value = "WINDOWS-" + re.cap (1);
+          if (codecs.contains ("IBM" + match.captured (1)))
+            adjusted_value = "IBM" + match.captured (1);
+          else if (codecs.contains ("WINDOWS-" + match.captured (1)))
+            adjusted_value = "WINDOWS-" + match.captured (1);
           else
             adjusted_value.clear ();
         }

--- a/libgui/src/variable-editor.cc	Wed Apr 12 11:21:28 2023 +0200
+++ b/libgui/src/variable-editor.cc	Wed Apr 12 12:02:25 2023 +0200
@@ -39,6 +39,7 @@
 #include <QMenu>
 #include <QPalette>
 #include <QPointer>
+#include <QRegularExpression>
 #include <QScreen>
 #include <QScrollBar>
 #include <QStackedWidget>
@@ -434,7 +435,7 @@
 
   if (name.endsWith (')') || name.endsWith ('}'))
     {
-      name.remove ( QRegExp ("[({][^({]*[)}]$)") );
+      name.remove (QRegularExpression {"[({][^({]*[)}]$)"});
       emit edit_variable_signal (name, octave_value ());
     }
 }