diff --git a/common/pm3process.cpp b/common/pm3process.cpp
index 08aef5a..8181353 100644
--- a/common/pm3process.cpp
+++ b/common/pm3process.cpp
@@ -14,7 +14,7 @@ PM3Process::PM3Process(QThread* thread, QObject* parent): QProcess(parent)
     connect(this, &PM3Process::readyRead, this, &PM3Process::onReadyRead);
 }
 
-void PM3Process::connectPM3(const QString path, const QString port)
+void PM3Process::connectPM3(const QString& path, const QString& port)
 {
     QString result;
     Util::ClientType clientType = Util::CLIENTTYPE_OFFICIAL;
@@ -93,7 +93,6 @@ void PM3Process::testThread()
     qDebug() << "PM3:" << QThread::currentThread();
 }
 
-
 qint64 PM3Process::write(QString data)
 {
     return QProcess::write(data.toLatin1());
diff --git a/common/pm3process.h b/common/pm3process.h
index 093ebfd..749c501 100644
--- a/common/pm3process.h
+++ b/common/pm3process.h
@@ -21,8 +21,8 @@ public:
     void testThread();
 
 public slots:
-    void connectPM3(const QString path, const QString port);
-    void setSerialListener(const QString &name, bool state);
+    void connectPM3(const QString& path, const QString& port);
+    void setSerialListener(const QString& name, bool state);
     qint64 write(QString data);
 private slots:
     void onTimeout();
@@ -34,8 +34,8 @@ private:
     QTimer* serialListener;
     QSerialPortInfo* portInfo;
 signals:
-    void PM3StatedChanged(bool st, QString info = "");
-    void newOutput(QString output);
+    void PM3StatedChanged(bool st, const QString& info = "");
+    void newOutput(const QString& output);
     void changeClientType(Util::ClientType);
 };
 
diff --git a/common/util.cpp b/common/util.cpp
index bb4f3ab..1da8256 100644
--- a/common/util.cpp
+++ b/common/util.cpp
@@ -9,7 +9,7 @@ Util::Util(QObject *parent) : QObject(parent)
     qRegisterMetaType<Util::ClientType>("Util::ClientType");
 }
 
-void Util::processOutput(QString output)
+void Util::processOutput(const QString& output)
 {
 //    qDebug() << "Util::processOutput:" << output;
     if(isRequiringOutput)
@@ -20,14 +20,14 @@ void Util::processOutput(QString output)
     emit refreshOutput(output);
 }
 
-void Util::execCMD(QString cmd)
+void Util::execCMD(const QString& cmd)
 {
     qDebug() << cmd;
     if(isRunning)
         emit write(cmd + "\r\n");
 }
 
-QString Util::execCMDWithOutput(QString cmd, ReturnTrigger trigger)
+QString Util::execCMDWithOutput(const QString& cmd, ReturnTrigger trigger)
 {
     bool isResultFound = false;
     QRegularExpression re;
diff --git a/common/util.h b/common/util.h
index bbf935a..04a4ec0 100644
--- a/common/util.h
+++ b/common/util.h
@@ -30,12 +30,12 @@ public:
             waitTime = time;
             expectedOutputs = QStringList();
         }
-        ReturnTrigger(QStringList outputs)
+        ReturnTrigger(const QStringList& outputs)
         {
             waitTime = 10000;
             expectedOutputs = outputs;
         }
-        ReturnTrigger(unsigned long time, QStringList outputs)
+        ReturnTrigger(unsigned long time, const QStringList& outputs)
         {
             waitTime = time;
             expectedOutputs = outputs;
@@ -46,12 +46,12 @@ public:
 
     explicit Util(QObject *parent = nullptr);
 
-    void execCMD(QString cmd);
-    QString execCMDWithOutput(QString cmd, ReturnTrigger trigger = 10000);
+    void execCMD(const QString& cmd);
+    QString execCMDWithOutput(const QString& cmd, ReturnTrigger trigger = 10000);
     void delay(unsigned int msec);
     ClientType getClientType();
 public slots:
-    void processOutput(QString output);
+    void processOutput(const QString& output);
     void setClientType(Util::ClientType clientType);
     void setRunningState(bool st);
 
@@ -63,7 +63,7 @@ private:
     ClientType clientType;
 signals:
     void refreshOutput(const QString& output);
-    void write(QString data);
+    void write(QString data); // connected to PM3Process::write(QString data);
 };
 
 #endif // UTIL_H
diff --git a/module/mifare.cpp b/module/mifare.cpp
index 92d377e..b07593e 100644
--- a/module/mifare.cpp
+++ b/module/mifare.cpp
@@ -872,7 +872,7 @@ void Mifare::data_clearKey(bool clearAll)
     }
 }
 
-bool Mifare::data_isKeyValid(const QString &key)
+bool Mifare::data_isKeyValid(const QString& key)
 {
     if(key.length() != 12)
         return false;
@@ -938,7 +938,7 @@ void Mifare::setCardType(int type)
     }
 }
 
-bool Mifare::data_loadDataFile(const QString &filename)
+bool Mifare::data_loadDataFile(const QString& filename)
 {
     QFile file(filename, this);
     if(file.open(QIODevice::ReadOnly))
@@ -985,7 +985,7 @@ bool Mifare::data_loadDataFile(const QString &filename)
     }
 }
 
-bool Mifare::data_loadKeyFile(const QString &filename)
+bool Mifare::data_loadKeyFile(const QString& filename)
 {
     QFile file(filename, this);
     if(file.open(QIODevice::ReadOnly))
@@ -1022,7 +1022,7 @@ bool Mifare::data_loadKeyFile(const QString &filename)
     }
 }
 
-QString Mifare::bin2text(const QByteArray &buff, int i, int length)
+QString Mifare::bin2text(const QByteArray& buff, int i, int length)
 {
     QString ret = "";
     char LByte, RByte;
@@ -1040,7 +1040,7 @@ QString Mifare::bin2text(const QByteArray &buff, int i, int length)
     return ret;
 }
 
-bool Mifare::data_saveDataFile(const QString &filename, bool isBin)
+bool Mifare::data_saveDataFile(const QString& filename, bool isBin)
 {
     QFile file(filename, this);
     if(file.open(QIODevice::WriteOnly))
@@ -1084,7 +1084,7 @@ bool Mifare::data_saveDataFile(const QString &filename, bool isBin)
     }
 }
 
-bool Mifare::data_saveKeyFile(const QString &filename, bool isBin)
+bool Mifare::data_saveKeyFile(const QString& filename, bool isBin)
 {
     QFile file(filename, this);
     if(file.open(QIODevice::WriteOnly))
@@ -1179,12 +1179,12 @@ void Mifare::data_data2Key()
     }
 }
 
-void Mifare::data_setData(int block, const QString &data)
+void Mifare::data_setData(int block, const QString& data)
 {
     dataList->replace(block, data);
 }
 
-void Mifare::data_setKey(int sector, KeyType keyType, const QString &key)
+void Mifare::data_setKey(int sector, KeyType keyType, const QString& key)
 {
     if(keyType == KEY_A)
         keyAList->replace(sector, key);
diff --git a/module/mifare.h b/module/mifare.h
index b328314..dfde298 100644
--- a/module/mifare.h
+++ b/module/mifare.h
@@ -106,9 +106,9 @@ public:
     void saveSniff(const QString& file);
     void data_fillKeys();
 
-    static QList<quint8> data_getACBits(const QString &text);
+    static QList<quint8> data_getACBits(const QString& text);
     static int data_b2s(int block);
-    static bool data_isACBitsValid(const QString &text, QList<quint8> *returnHalfBytes = nullptr);
+    static bool data_isACBitsValid(const QString& text, QList<quint8> *returnHalfBytes = nullptr);
 public slots:
 signals:
 
@@ -125,9 +125,9 @@ private:
     QRegularExpression* keyPattern;
     QString bin2text(const QByteArray& buff, int start, int length);
 
-    QString _readblk(int blockId, KeyType keyType, const QString &key, TargetType targetType = TARGET_MIFARE, int waitTime = 300);
-    QStringList _readsec(int sectorId, KeyType keyType, const QString &key, TargetType targetType = TARGET_MIFARE, int waitTime = 300);
-    bool _writeblk(int blockId, KeyType keyType, const QString &key, const QString &data, TargetType targetType = TARGET_MIFARE, int waitTime = 300);
+    QString _readblk(int blockId, KeyType keyType, const QString& key, TargetType targetType = TARGET_MIFARE, int waitTime = 300);
+    QStringList _readsec(int sectorId, KeyType keyType, const QString& key, TargetType targetType = TARGET_MIFARE, int waitTime = 300);
+    bool _writeblk(int blockId, KeyType keyType, const QString& key, const QString& data, TargetType targetType = TARGET_MIFARE, int waitTime = 300);
 };
 
 #endif // MIFARE_H
diff --git a/ui/mainwindow.cpp b/ui/mainwindow.cpp
index aac66f5..421a019 100644
--- a/ui/mainwindow.cpp
+++ b/ui/mainwindow.cpp
@@ -86,7 +86,7 @@ void MainWindow::on_PM3_connectButton_clicked()
     }
 }
 
-void MainWindow::onPM3StateChanged(bool st, QString info)
+void MainWindow::onPM3StateChanged(bool st, const QString& info)
 {
     pm3state = st;
     setState(st);
@@ -898,7 +898,7 @@ void MainWindow::signalInit()
     connect(stopButton, &QPushButton::clicked, this, &MainWindow::on_stopButton_clicked);
 }
 
-void MainWindow::setStatusBar(QLabel * target, const QString & text)
+void MainWindow::setStatusBar(QLabel * target, const QString& text)
 {
     if(target == PM3VersionBar)
         target->setText(tr("HW Version:") + text);
@@ -908,7 +908,7 @@ void MainWindow::setStatusBar(QLabel * target, const QString & text)
         target->setText(tr("State:") + text);
 }
 
-void MainWindow::setTableItem(QTableWidget * widget, int row, int column, const QString & text)
+void MainWindow::setTableItem(QTableWidget * widget, int row, int column, const QString& text)
 {
     if(widget->item(row, column) == nullptr)
         widget->setItem(row, column, new QTableWidgetItem());
@@ -993,7 +993,7 @@ void MainWindow::on_GroupBox_clicked(bool checked)
     settings->endGroup();
 }
 
-void MainWindow::saveClientPath(const QString & path)
+void MainWindow::saveClientPath(const QString& path)
 {
     settings->beginGroup("Client_Path");
     settings->setValue("path", path);
diff --git a/ui/mainwindow.h b/ui/mainwindow.h
index 55c8c6f..2c7fcd5 100644
--- a/ui/mainwindow.h
+++ b/ui/mainwindow.h
@@ -44,10 +44,10 @@ public:
     void initUI();
     bool eventFilter(QObject *watched, QEvent *event);
 public slots:
-    void refreshOutput(const QString &output);
-    void refreshCMD(const QString &cmd);
-    void setStatusBar(QLabel* target, const QString & text);
-    void onPM3StateChanged(bool st, QString info);
+    void refreshOutput(const QString& output);
+    void refreshCMD(const QString& cmd);
+    void setStatusBar(QLabel* target, const QString& text);
+    void onPM3StateChanged(bool st, const QString& info);
     void MF_onTypeChanged(int id, bool st);
 private slots:
 
@@ -175,12 +175,12 @@ private:
 
     void signalInit();
     void MF_widgetReset();
-    void setTableItem(QTableWidget *widget, int row, int column, const QString &text);
+    void setTableItem(QTableWidget *widget, int row, int column, const QString& text);
     void setState(bool st);
-    void saveClientPath(const QString &path);
+    void saveClientPath(const QString& path);
 signals:
-    void connectPM3(const QString path, const QString port);
+    void connectPM3(const QString& path, const QString& port);
     void killPM3();
-    void setSerialListener(const QString &name, bool state);
+    void setSerialListener(const QString& name, bool state);
 };
 #endif // MAINWINDOW_H
diff --git a/ui/mf_attack_hardnesteddialog.h b/ui/mf_attack_hardnesteddialog.h
index 0f13bf7..d120b2a 100644
--- a/ui/mf_attack_hardnesteddialog.h
+++ b/ui/mf_attack_hardnesteddialog.h
@@ -3,7 +3,8 @@
 
 #include <QDialog>
 
-namespace Ui {
+namespace Ui
+{
 class MF_Attack_hardnestedDialog;
 }
 
@@ -19,7 +20,7 @@ public:
 private:
     Ui::MF_Attack_hardnestedDialog *ui;
 signals:
-    void sendCMD(QString cmd);
+    void sendCMD(const QString& cmd);
 private slots:
     void on_buttonBox_accepted();
 };
diff --git a/ui/mf_sim_simdialog.h b/ui/mf_sim_simdialog.h
index 7fa53a1..49c9ba2 100644
--- a/ui/mf_sim_simdialog.h
+++ b/ui/mf_sim_simdialog.h
@@ -26,7 +26,7 @@ private:
     Ui::MF_Sim_simDialog *ui;
     int cardType;
 signals:
-    void sendCMD(QString cmd);
+    void sendCMD(const QString& cmd);
 private slots:
     void on_buttonBox_accepted();
 };
diff --git a/ui/mf_trailerdecoderdialog.h b/ui/mf_trailerdecoderdialog.h
index 93a6abd..e863f1c 100644
--- a/ui/mf_trailerdecoderdialog.h
+++ b/ui/mf_trailerdecoderdialog.h
@@ -23,11 +23,11 @@ public:
 
 private slots:
 
-    void on_accessBitsEdit_textChanged(const QString &arg1);
+    void on_accessBitsEdit_textChanged(const QString& arg1);
 
     void on_blockSizeChanged(int id, bool st);
 
-    void on_boxChanged(const QString &arg1);
+    void on_boxChanged(const QString& arg1);
 private:
     Ui::MF_trailerDecoderDialog *ui;
     QRegularExpressionValidator* validator;
diff --git a/ui/mf_uid_parameterdialog.h b/ui/mf_uid_parameterdialog.h
index ec580cb..85e9fc0 100644
--- a/ui/mf_uid_parameterdialog.h
+++ b/ui/mf_uid_parameterdialog.h
@@ -3,7 +3,8 @@
 
 #include <QDialog>
 
-namespace Ui {
+namespace Ui
+{
 class MF_UID_parameterDialog;
 }
 
@@ -18,7 +19,7 @@ public:
 private:
     Ui::MF_UID_parameterDialog *ui;
 signals:
-    void sendCMD(QString cmd);
+    void sendCMD(const QString& cmd);
 private slots:
     void on_buttonBox_accepted();
 };