fix typo and use pre-compiled regex

interface.cpp

@@ -535,7 +535,7 @@ QStringList Interface::list() {
   nl_socket_free(sock);
 
   // workaround for libnl issue: https://github.com/tgraf/libnl/issues/49
-  // find any interfaces libnl doesn't know about (e.g. USB wireless adapters after they're been unplugged and replugged)
+  // find any interfaces libnl doesn't know about (e.g. USB wireless adapters after they've been unplugged and replugged)
   QDir dir("/sys/class/net");
   QStringList interfaces = dir.entryList(QDir::Dirs | QDir::NoDotAndDotDot);
 

wireless.cpp

@@ -103,6 +103,7 @@ QObject(0),
 m_interface(interface),
 m_interfaceType(),
 m_bands(),
+m_noDigitRegex("[^\\d]"),
 m_isValid(false),
 m_isNL80211(false),
 m_iftype(NL80211_IFTYPE_UNSPECIFIED)
@@ -405,8 +406,7 @@ int Wireless::ChanToFreq(int channel) {
 */
 QString Wireless::ChanToFreq(QString channel, QString outputFormat) {
   QString freq;
-  QRegularExpression re("[^\\d]");
-  channel = channel.replace(re, "");
+  channel = channel.replace(m_noDigitRegex, "");
 
   if(outputFormat.isEmpty()) {
     bool ok = false;
@@ -442,8 +442,7 @@ int Wireless::FreqToChan(int frequency) {
 */
 QString Wireless::FreqToChan(QString frequency, QString outputFormat) {
   QString chan;
-  QRegularExpression re("[^\\d]");
-  frequency = frequency.replace(re, "");
+  frequency = frequency.replace(m_noDigitRegex, "");
 
   if(frequency.length() < 4) {
     for(int i = frequency.length() + 1; i <= 4; ++i) {

wireless.h

@@ -97,6 +97,7 @@ private:
   QString m_interface;
   QString m_interfaceType;
   QList<BandInfo> m_bands;
+  QRegularExpression m_noDigitRegex;
   bool m_isValid;
   bool m_isNL80211;
   nl80211_iftype m_iftype;