Fix clang-tidy warnings (detected by clang-tidy-18)

src/click/model/ipv4-click-routing.cc

@@ -86,7 +86,7 @@ Ipv4ClickRouting::DoInitialize()
         m_nodeName = name.str();
     }
 
-    NS_ASSERT(m_clickFile.length() > 0);
+    NS_ASSERT(!m_clickFile.empty());
 
     // Even though simclick_click_create() will halt programme execution
     // if it is unable to initialise a Click router, we play safe

src/internet/helper/internet-trace-helper.cc

@@ -59,8 +59,7 @@ PcapHelperForIpv4::EnablePcapIpv4(std::string prefix, Ipv4InterfaceContainer c)
 {
     for (Ipv4InterfaceContainer::Iterator i = c.Begin(); i != c.End(); ++i)
     {
-        std::pair<Ptr<Ipv4>, uint32_t> pair = *i;
-        EnablePcapIpv4(prefix, pair.first, pair.second, false);
+        EnablePcapIpv4(prefix, (*i).first, (*i).second, false);
     }
 }
 
@@ -200,8 +199,7 @@ AsciiTraceHelperForIpv4::EnableAsciiIpv4Impl(Ptr<OutputStreamWrapper> stream,
 {
     for (Ipv4InterfaceContainer::Iterator i = c.Begin(); i != c.End(); ++i)
     {
-        std::pair<Ptr<Ipv4>, uint32_t> pair = *i;
-        EnableAsciiIpv4Internal(stream, prefix, pair.first, pair.second, false);
+        EnableAsciiIpv4Internal(stream, prefix, (*i).first, (*i).second, false);
     }
 }
 
@@ -341,8 +339,7 @@ PcapHelperForIpv6::EnablePcapIpv6(std::string prefix, Ipv6InterfaceContainer c)
 {
     for (Ipv6InterfaceContainer::Iterator i = c.Begin(); i != c.End(); ++i)
     {
-        std::pair<Ptr<Ipv6>, uint32_t> pair = *i;
-        EnablePcapIpv6(prefix, pair.first, pair.second, false);
+        EnablePcapIpv6(prefix, (*i).first, (*i).second, false);
     }
 }
 
@@ -482,8 +479,7 @@ AsciiTraceHelperForIpv6::EnableAsciiIpv6Impl(Ptr<OutputStreamWrapper> stream,
 {
     for (Ipv6InterfaceContainer::Iterator i = c.Begin(); i != c.End(); ++i)
     {
-        std::pair<Ptr<Ipv6>, uint32_t> pair = *i;
-        EnableAsciiIpv6Internal(stream, prefix, pair.first, pair.second, false);
+        EnableAsciiIpv6Internal(stream, prefix, (*i).first, (*i).second, false);
     }
 }
 

src/internet/model/tcp-header.cc

@@ -44,7 +44,7 @@ TcpHeader::FlagsToString(uint8_t flags, const std::string& delimiter)
     {
         if (flags & (1 << i))
         {
-            if (flagsDescription.length() > 0)
+            if (!flagsDescription.empty())
             {
                 flagsDescription += delimiter;
             }

src/mobility/helper/ns2-mobility-helper.cc

@@ -523,7 +523,7 @@ ParseNs2Line(const std::string& str)
     {
         std::string x;
         s >> x;
-        if (x.length() == 0)
+        if (x.empty())
         {
             continue;
         }

src/visualizer/model/pyviz.cc

@@ -51,7 +51,7 @@ PathSplit(std::string str)
         }
         str = str.substr(cutAt + 1);
     }
-    if (str.length() > 0)
+    if (!str.empty())
     {
         results.push_back(str);
     }