diff --git a/kfileio.cpp b/kfileio.cpp
index bb3bef1af..11d4b6353 100644
--- a/kfileio.cpp
+++ b/kfileio.cpp
@@ -15,19 +15,14 @@
 
 
 //-----------------------------------------------------------------------------
-static void msgDialog(const char* msg, const char* arg=NULL)
+static void msgDialog(const QString &msg)
 {
-  QString str;
-
-  if (arg) str.sprintf(msg, arg);
-  else str = msg;
-
-  KMessageBox::sorry(0, str, i18n("File I/O Error"));
+  KMessageBox::sorry(0, msg, i18n("File I/O Error"));
 }
 
 
 //-----------------------------------------------------------------------------
-QString kFileToString(const char* aFileName, bool aEnsureNL, bool aVerbose)
+QString kFileToString(const QString &aFileName, bool aEnsureNL, bool aVerbose)
 {
   QCString result;
   QFileInfo info(aFileName);
@@ -42,22 +37,20 @@ QString kFileToString(const char* aFileName, bool aEnsureNL, bool aVerbose)
   if (!info.exists())
   {
     if (aVerbose)
-      msgDialog(i18n("The specified file does not exist:\n%s"),
-		aFileName);
+      msgDialog(i18n("The specified file does not exist:\n%1").arg(aFileName));
     return QString::null;
   }
   if (info.isDir())
   {
     if (aVerbose)
-      msgDialog(i18n("This is a directory and not a file:\n%s"),
-		aFileName);
+      msgDialog(i18n("This is a directory and not a file:\n%1").arg(aFileName));
     return QString::null;
   }
   if (!info.isReadable())
   {
     if (aVerbose)
       msgDialog(i18n("You do not have read permissions "
-				   "to the file:\n%s"), aFileName);
+				   "to the file:\n%1").arg(aFileName));
     return QString::null;
   }
   if (len <= 0) return QString::null;
@@ -67,13 +60,13 @@ QString kFileToString(const char* aFileName, bool aEnsureNL, bool aVerbose)
     if (aVerbose) switch(file.status())
     {
     case IO_ReadError:
-      msgDialog(i18n("Could not read file:\n%s"), aFileName);
+      msgDialog(i18n("Could not read file:\n%1").arg(aFileName));
       break;
     case IO_OpenError:
-      msgDialog(i18n("Could not open file:\n%s"), aFileName);
+      msgDialog(i18n("Could not open file:\n%1").arg(aFileName));
       break;
     default:
-      msgDialog(i18n("Error while reading file:\n%s"),aFileName);
+      msgDialog(i18n("Error while reading file:\n%1").arg(aFileName));
     }
     return QString::null;
   }
@@ -89,8 +82,7 @@ QString kFileToString(const char* aFileName, bool aEnsureNL, bool aVerbose)
 
   if (readLen < len)
   {
-    QString msg;
-    msg = i18n("Could only read %1 bytes of %2.")
+    QString msg = i18n("Could only read %1 bytes of %2.")
 		.arg(readLen).arg(len);
     msgDialog(msg);
     return QString::null;
@@ -100,7 +92,7 @@ QString kFileToString(const char* aFileName, bool aEnsureNL, bool aVerbose)
 }
 
 //-----------------------------------------------------------------------------
-QByteArray kFileToBytes(const char* aFileName, bool aVerbose)
+QByteArray kFileToBytes(const QString &aFileName, bool aVerbose)
 {
   QByteArray result;
   QFileInfo info(aFileName);
@@ -115,22 +107,22 @@ QByteArray kFileToBytes(const char* aFileName, bool aVerbose)
   if (!info.exists())
   {
     if (aVerbose)
-      msgDialog(i18n("The specified file does not exist:\n%s"),
-		aFileName);
+      msgDialog(i18n("The specified file does not exist:\n%1")
+		.arg(aFileName));
     return result;
   }
   if (info.isDir())
   {
     if (aVerbose)
-      msgDialog(i18n("This is a directory and not a file:\n%s"),
-		aFileName);
+      msgDialog(i18n("This is a directory and not a file:\n%1")
+		.arg(aFileName));
     return result;
   }
   if (!info.isReadable())
   {
     if (aVerbose)
       msgDialog(i18n("You do not have read permissions "
-				   "to the file:\n%s"), aFileName);
+				   "to the file:\n%1").arg(aFileName));
     return result;
   }
   if (len <= 0) return result;
@@ -140,13 +132,13 @@ QByteArray kFileToBytes(const char* aFileName, bool aVerbose)
     if (aVerbose) switch(file.status())
     {
     case IO_ReadError:
-      msgDialog(i18n("Could not read file:\n%s"), aFileName);
+      msgDialog(i18n("Could not read file:\n%1").arg(aFileName));
       break;
     case IO_OpenError:
-      msgDialog(i18n("Could not open file:\n%s"), aFileName);
+      msgDialog(i18n("Could not open file:\n%1").arg(aFileName));
       break;
     default:
-      msgDialog(i18n("Error while reading file:\n%s"),aFileName);
+      msgDialog(i18n("Error while reading file:\n%1").arg(aFileName));
     }
     return result;
   }
@@ -174,7 +166,7 @@ QByteArray kFileToBytes(const char* aFileName, bool aVerbose)
 //-----------------------------------------------------------------------------
 static
 bool kBytesToFile(const char* aBuffer, int len,
-		   const char* aFileName, 
+		   const QString &aFileName, 
 		   bool aAskIfExists, bool aBackup, bool aVerbose)
 {
   QFile file(aFileName);
@@ -208,7 +200,8 @@ bool kBytesToFile(const char* aBuffer, int len,
 	// failed to rename file
 	if (!aVerbose) return FALSE;
 	rc = KMessageBox::warningContinueCancel(0,
-	     i18n("Failed to make a backup copy of %s.\nContinue anyway ?"),
+	     i18n("Failed to make a backup copy of %1.\nContinue anyway ?")
+	     .arg(aFileName),
              i18n("Save to file"), i18n("&Save"));
 	if (rc != KMessageBox::Continue) return FALSE;
       }
@@ -220,14 +213,14 @@ bool kBytesToFile(const char* aBuffer, int len,
     if (aVerbose) switch(file.status())
     {
     case IO_WriteError:
-      msgDialog(i18n("Could not write to file:\n%s"), aFileName);
+      msgDialog(i18n("Could not write to file:\n%1").arg(aFileName));
       break;
     case IO_OpenError:
-      msgDialog(i18n("Could not open file for writing:\n%s"),
-		aFileName);
+      msgDialog(i18n("Could not open file for writing:\n%1")
+		.arg(aFileName));
       break;
     default:
-      msgDialog(i18n("Error while writing file:\n%s"),aFileName);
+      msgDialog(i18n("Error while writing file:\n%1").arg(aFileName));
     }
     return FALSE;
   }
@@ -236,13 +229,12 @@ bool kBytesToFile(const char* aBuffer, int len,
 
   if (writeLen < 0) 
   {
-    msgDialog(i18n("Could not write to file:\n%s"), aFileName);
+    msgDialog(i18n("Could not write to file:\n%1").arg(aFileName));
     return FALSE;
   }
   else if (writeLen < len)
   {
-    QString msg;
-    msg = i18n("Could only write %1 bytes of %2.")
+    QString msg = i18n("Could only write %1 bytes of %2.")
 		.arg(writeLen).arg(len);
     msgDialog(msg);
     return FALSE;
@@ -251,14 +243,14 @@ bool kBytesToFile(const char* aBuffer, int len,
   return TRUE;
 }
 
-bool kCStringToFile(const QCString& aBuffer, const char* aFileName, 
+bool kCStringToFile(const QCString& aBuffer, const QString &aFileName, 
 		   bool aAskIfExists, bool aBackup, bool aVerbose)
 {
     return kBytesToFile(aBuffer, aBuffer.length(), aFileName, aAskIfExists,
 	aBackup, aVerbose);
 }
 
-bool kByteArrayToFile(const QByteArray& aBuffer, const char* aFileName, 
+bool kByteArrayToFile(const QByteArray& aBuffer, const QString &aFileName, 
 		   bool aAskIfExists, bool aBackup, bool aVerbose)
 {
     return kBytesToFile(aBuffer, aBuffer.size(), aFileName, aAskIfExists,
diff --git a/kfileio.h b/kfileio.h
index 281f7c8f6..4838fc631 100644
--- a/kfileio.h
+++ b/kfileio.h
@@ -16,10 +16,10 @@
  * byte longer than the file itself.
  * If ensureNewline is TRUE the string will always have a trailing newline.
  */
-QString kFileToString(const char* fileName, bool ensureNewline=TRUE,
+QString kFileToString(const QString &fileName, bool ensureNewline=TRUE,
 		      bool withDialogs=TRUE);
 
-QByteArray kFileToBytes(const char* fileName, bool withDialogs=TRUE);
+QByteArray kFileToBytes(const QString &fileName, bool withDialogs=TRUE);
 
 
 /** Save a file. If withDialogs is FALSE no warning dialogs are opened if 
@@ -27,11 +27,11 @@ QByteArray kFileToBytes(const char* fileName, bool withDialogs=TRUE);
  * Replaces existing files without warning if askIfExists==FALSE.
  * Makes a copy if the file exists to filename~ if createBackup==TRUE.
  */
-bool kCStringToFile(const QCString& buffer, const char* fileName, 
+bool kCStringToFile(const QCString& buffer, const QString &fileName, 
 		   bool askIfExists=FALSE, bool createBackup=TRUE,
 		   bool withDialogs=TRUE);
 // Does not stop at NUL
-bool kByteArrayToFile(const QByteArray& buffer, const char* fileName, 
+bool kByteArrayToFile(const QByteArray& buffer, const QString &fileName, 
 		   bool askIfExists=FALSE, bool createBackup=TRUE,
 		   bool withDialogs=TRUE);
 
diff --git a/kmaddrbook.cpp b/kmaddrbook.cpp
index ebcf943d0..6a48f858b 100644
--- a/kmaddrbook.cpp
+++ b/kmaddrbook.cpp
@@ -84,10 +84,10 @@ void KMAddrBook::readConfig(void)
 
 
 //-----------------------------------------------------------------------------
-int KMAddrBook::load(const char* aFileName)
+int KMAddrBook::load(const QString &aFileName)
 {
   char line[256];
-  const char* fname = (aFileName ? aFileName : (const char*)mDefaultFileName);
+  QString fname = aFileName.isNull() ? mDefaultFileName : aFileName;
   QFile file(fname);
   int rc;
 
@@ -115,15 +115,14 @@ int KMAddrBook::load(const char* aFileName)
 
 
 //-----------------------------------------------------------------------------
-int KMAddrBook::store(const char* aFileName)
+int KMAddrBook::store(const QString &aFileName)
 {
   const char* addr;
-  const char* fname = (aFileName ? aFileName : (const char*)mDefaultFileName);
+  QString fname = aFileName.isNull() ? mDefaultFileName : aFileName;
   QFile file(fname);
 
-
   //assert(fname != NULL);
-  if(!fname)
+  if(fname.isNull())
     return IO_FatalError;
 
   if (!file.open(IO_ReadWrite|IO_Truncate)) return fileError(file.status());
@@ -146,21 +145,21 @@ int KMAddrBook::store(const char* aFileName)
 //-----------------------------------------------------------------------------
 int KMAddrBook::fileError(int status) const
 {
-  QString msg, str;
+  QString msg;
 
   switch(status)
   {
   case IO_ReadError:
-    msg = i18n("Could not read file:\n%s");
+    msg = i18n("Could not read file:\n%1");
     break;
   case IO_OpenError:
-    msg = i18n("Could not open file:\n%s");
+    msg = i18n("Could not open file:\n%1");
     break;
   default:
-    msg = i18n("Error while writing file:\n%s");
+    msg = i18n("Error while writing file:\n%1");
   }
 
-  str.sprintf(msg, mDefaultFileName.data());
+  QString str = msg.arg(mDefaultFileName);
   KMessageBox::sorry(0, str, i18n("File I/O Error"));
 
   return status;
diff --git a/kmaddrbook.h b/kmaddrbook.h
index b287c36d4..057cf4d0c 100644
--- a/kmaddrbook.h
+++ b/kmaddrbook.h
@@ -22,10 +22,10 @@ public:
   virtual void remove(const QString address);
 
   /** Returns first address in addressbook or NULL if addressbook is empty. */
-  virtual const char* first(void) { return KMAddrBookInherited::first(); }
+  virtual QString first(void) { return KMAddrBookInherited::first(); }
 
   /** Returns next address in addressbook or NULL. */
-  virtual const char* next(void) { return KMAddrBookInherited::next(); }
+  virtual QString next(void) { return KMAddrBookInherited::next(); }
 
   /** Clear addressbook (remove the contents). */
   virtual void clear(void);
@@ -34,12 +34,12 @@ public:
     file is used if no filename is given.
     Returns IO_Ok on success and an IO device status on failure -- see
     QIODevice::status(). */
-  virtual int load(const char* fileName=NULL);
+  virtual int load(const QString &fileName=QString::null);
 
   /** Store addressbook in file or in same file of last load() call
     if no filename is given. Returns IO_Ok on success and an IO device
     status on failure -- see QIODevice::status(). */
-  virtual int store(const char* fileName=NULL);
+  virtual int store(const QString &fileName=QString::null);
 
   /** Read/write configuration options. Uses the group "Addressbook"
     in the app's config file. */
diff --git a/kmfldsearch.cpp b/kmfldsearch.cpp
index 4a3553855..fe1fad6e3 100644
--- a/kmfldsearch.cpp
+++ b/kmfldsearch.cpp
@@ -138,10 +138,11 @@ void KMFldSearch::updStatus(void)
   QString str;
 
   if (!mSearching)
-    str.sprintf(i18n("Done, %d matches"), mNumMatches);
+    str = i18n("Done, %1 matches").arg(mNumMatches);
   else
-    str.sprintf(i18n("%d matches, searching in %s"), mNumMatches,
-		(const char*)mSearchFolder);
+    str = i18n("%1 matches, searching in %2")
+		.arg(mNumMatches)
+		.arg(mSearchFolder);
   mLblStatus->setText(str);
 }