use const references where appropriate

21 files changed, 61 insertions, 63 deletions

diff --git a/src/alert.cpp b/src/alert.cpp
index aa7ac748da..ad81e74226 100644
--- a/src/alert.cpp
+++ b/src/alert.cpp
@@ -50,7 +50,7 @@ std::string CUnsignedAlert::ToString() const
     BOOST_FOREACH(int n, setCancel)
         strSetCancel += strprintf("%d ", n);
     std::string strSetSubVer;
-    BOOST_FOREACH(std::string str, setSubVer)
+    BOOST_FOREACH(const std::string& str, setSubVer)
         strSetSubVer += "\"" + str + "\" ";
     return strprintf(
         "CAlert(\n"
@@ -110,7 +110,7 @@ bool CAlert::Cancels(const CAlert& alert) const
     return (alert.nID <= nCancel || setCancel.count(alert.nID));
 }
 
-bool CAlert::AppliesTo(int nVersion, std::string strSubVerIn) const
+bool CAlert::AppliesTo(int nVersion, const std::string& strSubVerIn) const
 {
     // TODO: rework for client-version-embedded-in-strSubVer ?
     return (IsInEffect() &&
diff --git a/src/alert.h b/src/alert.h
index 746967c4af..4f9fff9181 100644
--- a/src/alert.h
+++ b/src/alert.h
@@ -97,7 +97,7 @@ public:
     uint256 GetHash() const;
     bool IsInEffect() const;
     bool Cancels(const CAlert& alert) const;
-    bool AppliesTo(int nVersion, std::string strSubVerIn) const;
+    bool AppliesTo(int nVersion, const std::string& strSubVerIn) const;
     bool AppliesToMe() const;
     bool RelayTo(CNode* pnode) const;
     bool CheckSignature(const std::vector<unsigned char>& alertKey) const;
diff --git a/src/consensus/validation.h b/src/consensus/validation.h
index c92bec4fae..a97d983a31 100644
--- a/src/consensus/validation.h
+++ b/src/consensus/validation.h
@@ -48,7 +48,7 @@ public:
                  unsigned char _chRejectCode=0, std::string _strRejectReason="") {
         return DoS(0, ret, _chRejectCode, _strRejectReason);
     }
-    bool Error(std::string strRejectReasonIn="") {
+    bool Error(const std::string& strRejectReasonIn) {
         if (mode == MODE_VALID)
             strRejectReason = strRejectReasonIn;
         mode = MODE_ERROR;
diff --git a/src/core_io.h b/src/core_io.h
index 0989cf7437..115e3199dc 100644
--- a/src/core_io.h
+++ b/src/core_io.h
@@ -15,7 +15,7 @@ class uint256;
 class UniValue;
 
 // core_read.cpp
-extern CScript ParseScript(std::string s);
+extern CScript ParseScript(const std::string& s);
 extern bool DecodeHexTx(CTransaction& tx, const std::string& strHexTx);
 extern bool DecodeHexBlk(CBlock&, const std::string& strHexBlk);
 extern uint256 ParseHashUV(const UniValue& v, const std::string& strName);
diff --git a/src/core_read.cpp b/src/core_read.cpp
index e064955ff0..f762f2c3b7 100644
--- a/src/core_read.cpp
+++ b/src/core_read.cpp
@@ -22,7 +22,7 @@
 
 using namespace std;
 
-CScript ParseScript(std::string s)
+CScript ParseScript(const std::string& s)
 {
     CScript result;
 
diff --git a/src/init.cpp b/src/init.cpp
index 35284992ed..02dca57031 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -535,7 +535,7 @@ void ThreadImport(std::vector<boost::filesystem::path> vImportFiles)
     }
 
     // -loadblock=
-    BOOST_FOREACH(boost::filesystem::path &path, vImportFiles) {
+    BOOST_FOREACH(const boost::filesystem::path& path, vImportFiles) {
         FILE *file = fopen(path.string().c_str(), "rb");
         if (file) {
             CImportingNow imp;
@@ -929,15 +929,15 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 
         std::string warningString;
         std::string errorString;
-        
+
         if (!CWallet::Verify(strWalletFile, warningString, errorString))
             return false;
-        
+
         if (!warningString.empty())
             InitWarning(warningString);
         if (!errorString.empty())
             return InitError(warningString);
-        
+
     } // (!fDisableWallet)
 #endif // ENABLE_WALLET
     // ********************************************************* Step 6: network initialization
@@ -946,7 +946,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 
     if (mapArgs.count("-onlynet")) {
         std::set<enum Network> nets;
-        BOOST_FOREACH(std::string snet, mapMultiArgs["-onlynet"]) {
+        BOOST_FOREACH(const std::string& snet, mapMultiArgs["-onlynet"]) {
             enum Network net = ParseNetwork(snet);
             if (net == NET_UNROUTABLE)
                 return InitError(strprintf(_("Unknown network specified in -onlynet: '%s'"), snet));
@@ -1003,13 +1003,13 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     bool fBound = false;
     if (fListen) {
         if (mapArgs.count("-bind") || mapArgs.count("-whitebind")) {
-            BOOST_FOREACH(std::string strBind, mapMultiArgs["-bind"]) {
+            BOOST_FOREACH(const std::string& strBind, mapMultiArgs["-bind"]) {
                 CService addrBind;
                 if (!Lookup(strBind.c_str(), addrBind, GetListenPort(), false))
                     return InitError(strprintf(_("Cannot resolve -bind address: '%s'"), strBind));
                 fBound |= Bind(addrBind, (BF_EXPLICIT | BF_REPORT_ERROR));
             }
-            BOOST_FOREACH(std::string strBind, mapMultiArgs["-whitebind"]) {
+            BOOST_FOREACH(const std::string& strBind, mapMultiArgs["-whitebind"]) {
                 CService addrBind;
                 if (!Lookup(strBind.c_str(), addrBind, 0, false))
                     return InitError(strprintf(_("Cannot resolve -whitebind address: '%s'"), strBind));
@@ -1029,7 +1029,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     }
 
     if (mapArgs.count("-externalip")) {
-        BOOST_FOREACH(string strAddr, mapMultiArgs["-externalip"]) {
+        BOOST_FOREACH(const std::string& strAddr, mapMultiArgs["-externalip"]) {
             CService addrLocal(strAddr, GetListenPort(), fNameLookup);
             if (!addrLocal.IsValid())
                 return InitError(strprintf(_("Cannot resolve -externalip address: '%s'"), strAddr));
@@ -1037,7 +1037,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
         }
     }
 
-    BOOST_FOREACH(string strDest, mapMultiArgs["-seednode"])
+    BOOST_FOREACH(const std::string& strDest, mapMultiArgs["-seednode"])
         AddOneShot(strDest);
 
     // ********************************************************* Step 7: load block chain
@@ -1362,7 +1362,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     std::vector<boost::filesystem::path> vImportFiles;
     if (mapArgs.count("-loadblock"))
     {
-        BOOST_FOREACH(string strFile, mapMultiArgs["-loadblock"])
+        BOOST_FOREACH(const std::string& strFile, mapMultiArgs["-loadblock"])
             vImportFiles.push_back(strFile);
     }
     threadGroup.create_thread(boost::bind(&ThreadImport, vImportFiles));
diff --git a/src/main.cpp b/src/main.cpp
index 760cda5dee..e9a5f7efd9 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -693,7 +693,7 @@ bool CheckFinalTx(const CTransaction &tx)
 /**
  * Check transaction inputs to mitigate two
  * potential denial-of-service attacks:
- * 
+ *
  * 1. scriptSigs with extra data stuffed into them,
  *    not consumed by scriptPubKey (or P2SH script)
  * 2. P2SH scripts with a crazy number of expensive
@@ -2148,7 +2148,7 @@ static int64_t nTimeFlush = 0;
 static int64_t nTimeChainState = 0;
 static int64_t nTimePostConnect = 0;
 
-/** 
+/**
  * Connect a new block to chainActive. pblock is either NULL or a pointer to a CBlock
  * corresponding to pindexNew, to bypass loading it again from disk.
  */
@@ -3696,7 +3696,7 @@ void static CheckBlockIndex()
 // CAlert
 //
 
-string GetWarnings(string strFor)
+std::string GetWarnings(const std::string& strFor)
 {
     int nPriority = 0;
     string strStatusBar;
diff --git a/src/main.h b/src/main.h
index 669ea7128a..abaedae207 100644
--- a/src/main.h
+++ b/src/main.h
@@ -190,7 +190,7 @@ void PartitionCheck(bool (*initialDownloadCheck)(), CCriticalSection& cs, const
 /** Check whether we are doing an initial block download (synchronizing from disk or network) */
 bool IsInitialBlockDownload();
 /** Format a string that describes several potential problems detected by the core */
-std::string GetWarnings(std::string strFor);
+std::string GetWarnings(const std::string& strFor);
 /** Retrieve a transaction (from memory pool, or from disk, if possible) */
 bool GetTransaction(const uint256 &hash, CTransaction &tx, uint256 &hashBlock, bool fAllowSlow = false);
 /** Find the best known block, and make it the tip of the block chain */
diff --git a/src/net.cpp b/src/net.cpp
index 3908be6824..42ac0e50ea 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -107,7 +107,7 @@ boost::condition_variable messageHandlerCondition;
 static CNodeSignals g_signals;
 CNodeSignals& GetNodeSignals() { return g_signals; }
 
-void AddOneShot(string strDest)
+void AddOneShot(const std::string& strDest)
 {
     LOCK(cs_vOneShots);
     vOneShots.push_back(strDest);
@@ -1124,7 +1124,7 @@ void ThreadDNSAddressSeed()
             vector<CAddress> vAdd;
             if (LookupHost(seed.host.c_str(), vIPs))
             {
-                BOOST_FOREACH(CNetAddr& ip, vIPs)
+                BOOST_FOREACH(const CNetAddr& ip, vIPs)
                 {
                     int nOneDay = 24*3600;
                     CAddress addr = CAddress(CService(ip, Params().GetDefaultPort()));
@@ -1188,7 +1188,7 @@ void ThreadOpenConnections()
         for (int64_t nLoop = 0;; nLoop++)
         {
             ProcessOneShot();
-            BOOST_FOREACH(string strAddr, mapMultiArgs["-connect"])
+            BOOST_FOREACH(const std::string& strAddr, mapMultiArgs["-connect"])
             {
                 CAddress addr;
                 OpenNetworkConnection(addr, NULL, strAddr.c_str());
@@ -1291,10 +1291,10 @@ void ThreadOpenAddedConnections()
             list<string> lAddresses(0);
             {
                 LOCK(cs_vAddedNodes);
-                BOOST_FOREACH(string& strAddNode, vAddedNodes)
+                BOOST_FOREACH(const std::string& strAddNode, vAddedNodes)
                     lAddresses.push_back(strAddNode);
             }
-            BOOST_FOREACH(string& strAddNode, lAddresses) {
+            BOOST_FOREACH(const std::string& strAddNode, lAddresses) {
                 CAddress addr;
                 CSemaphoreGrant grant(*semOutbound);
                 OpenNetworkConnection(addr, &grant, strAddNode.c_str());
@@ -1309,20 +1309,19 @@ void ThreadOpenAddedConnections()
         list<string> lAddresses(0);
         {
             LOCK(cs_vAddedNodes);
-            BOOST_FOREACH(string& strAddNode, vAddedNodes)
+            BOOST_FOREACH(const std::string& strAddNode, vAddedNodes)
                 lAddresses.push_back(strAddNode);
         }
 
         list<vector<CService> > lservAddressesToAdd(0);
-        BOOST_FOREACH(string& strAddNode, lAddresses)
-        {
+        BOOST_FOREACH(const std::string& strAddNode, lAddresses) {
             vector<CService> vservNode(0);
             if(Lookup(strAddNode.c_str(), vservNode, Params().GetDefaultPort(), fNameLookup, 0))
             {
                 lservAddressesToAdd.push_back(vservNode);
                 {
                     LOCK(cs_setservAddNodeAddresses);
-                    BOOST_FOREACH(CService& serv, vservNode)
+                    BOOST_FOREACH(const CService& serv, vservNode)
                         setservAddNodeAddresses.insert(serv);
                 }
             }
@@ -1333,7 +1332,7 @@ void ThreadOpenAddedConnections()
             LOCK(cs_vNodes);
             BOOST_FOREACH(CNode* pnode, vNodes)
                 for (list<vector<CService> >::iterator it = lservAddressesToAdd.begin(); it != lservAddressesToAdd.end(); it++)
-                    BOOST_FOREACH(CService& addrNode, *(it))
+                    BOOST_FOREACH(const CService& addrNode, *(it))
                         if (pnode->addr == addrNode)
                         {
                             it = lservAddressesToAdd.erase(it);
@@ -1906,7 +1905,7 @@ bool CAddrDB::Read(CAddrMan& addr)
 unsigned int ReceiveFloodSize() { return 1000*GetArg("-maxreceivebuffer", 5*1000); }
 unsigned int SendBufferSize() { return 1000*GetArg("-maxsendbuffer", 1*1000); }
 
-CNode::CNode(SOCKET hSocketIn, CAddress addrIn, std::string addrNameIn, bool fInboundIn) :
+CNode::CNode(SOCKET hSocketIn, const CAddress& addrIn, const std::string& addrNameIn, bool fInboundIn) :
     ssSend(SER_NETWORK, INIT_PROTO_VERSION),
     addrKnown(5000, 0.001, insecure_rand()),
     setInventoryKnown(SendBufferSize() / 1000)
diff --git a/src/net.h b/src/net.h
index 17502b97eb..938f2376f7 100644
--- a/src/net.h
+++ b/src/net.h
@@ -63,7 +63,7 @@ static const size_t MAPASKFOR_MAX_SZ = MAX_INV_SZ;
 unsigned int ReceiveFloodSize();
 unsigned int SendBufferSize();
 
-void AddOneShot(std::string strDest);
+void AddOneShot(const std::string& strDest);
 void AddressCurrentlyConnected(const CService& addr);
 CNode* FindNode(const CNetAddr& ip);
 CNode* FindNode(const std::string& addrName);
@@ -321,7 +321,7 @@ public:
     // Whether a ping is requested.
     bool fPingQueued;
 
-    CNode(SOCKET hSocketIn, CAddress addrIn, std::string addrNameIn = "", bool fInboundIn=false);
+    CNode(SOCKET hSocketIn, const CAddress &addrIn, const std::string &addrNameIn = "", bool fInboundIn = false);
     ~CNode();
 
 private:
diff --git a/src/rpcmining.cpp b/src/rpcmining.cpp
index 76d90a3f7e..51a8bbb9c4 100644
--- a/src/rpcmining.cpp
+++ b/src/rpcmining.cpp
@@ -523,8 +523,7 @@ UniValue getblocktemplate(const UniValue& params, bool fHelp)
     UniValue transactions(UniValue::VARR);
     map<uint256, int64_t> setTxIndex;
     int i = 0;
-    BOOST_FOREACH (CTransaction& tx, pblock->vtx)
-    {
+    BOOST_FOREACH (const CTransaction& tx, pblock->vtx) {
         uint256 txHash = tx.GetHash();
         setTxIndex[txHash] = i++;
 
diff --git a/src/rpcnet.cpp b/src/rpcnet.cpp
index 59253e72af..a36831de2a 100644
--- a/src/rpcnet.cpp
+++ b/src/rpcnet.cpp
@@ -253,19 +253,20 @@ UniValue getaddednodeinfo(const UniValue& params, bool fHelp)
     if (params.size() == 1)
     {
         LOCK(cs_vAddedNodes);
-        BOOST_FOREACH(string& strAddNode, vAddedNodes)
+        BOOST_FOREACH(const std::string& strAddNode, vAddedNodes)
             laddedNodes.push_back(strAddNode);
     }
     else
     {
         string strNode = params[1].get_str();
         LOCK(cs_vAddedNodes);
-        BOOST_FOREACH(string& strAddNode, vAddedNodes)
+        BOOST_FOREACH(const std::string& strAddNode, vAddedNodes) {
             if (strAddNode == strNode)
             {
                 laddedNodes.push_back(strAddNode);
                 break;
             }
+        }
         if (laddedNodes.size() == 0)
             throw JSONRPCError(RPC_CLIENT_NODE_NOT_ADDED, "Error: Node has not been added.");
     }
@@ -273,8 +274,7 @@ UniValue getaddednodeinfo(const UniValue& params, bool fHelp)
     UniValue ret(UniValue::VARR);
     if (!fDns)
     {
-        BOOST_FOREACH(string& strAddNode, laddedNodes)
-        {
+        BOOST_FOREACH (const std::string& strAddNode, laddedNodes) {
             UniValue obj(UniValue::VOBJ);
             obj.push_back(Pair("addednode", strAddNode));
             ret.push_back(obj);
@@ -283,8 +283,7 @@ UniValue getaddednodeinfo(const UniValue& params, bool fHelp)
     }
 
     list<pair<string, vector<CService> > > laddedAddreses(0);
-    BOOST_FOREACH(string& strAddNode, laddedNodes)
-    {
+    BOOST_FOREACH(const std::string& strAddNode, laddedNodes) {
         vector<CService> vservNode(0);
         if(Lookup(strAddNode.c_str(), vservNode, Params().GetDefaultPort(), fNameLookup, 0))
             laddedAddreses.push_back(make_pair(strAddNode, vservNode));
@@ -306,12 +305,11 @@ UniValue getaddednodeinfo(const UniValue& params, bool fHelp)
 
         UniValue addresses(UniValue::VARR);
         bool fConnected = false;
-        BOOST_FOREACH(CService& addrNode, it->second)
-        {
+        BOOST_FOREACH(const CService& addrNode, it->second) {
             bool fFound = false;
             UniValue node(UniValue::VOBJ);
             node.push_back(Pair("address", addrNode.ToString()));
-            BOOST_FOREACH(CNode* pnode, vNodes)
+            BOOST_FOREACH(CNode* pnode, vNodes) {
                 if (pnode->addr == addrNode)
                 {
                     fFound = true;
@@ -319,6 +317,7 @@ UniValue getaddednodeinfo(const UniValue& params, bool fHelp)
                     node.push_back(Pair("connected", pnode->fInbound ? "inbound" : "outbound"));
                     break;
                 }
+            }
             if (!fFound)
                 node.push_back(Pair("connected", "false"));
             addresses.push_back(node);
diff --git a/src/rpcserver.cpp b/src/rpcserver.cpp
index a92ec0b29b..e6bf008618 100644
--- a/src/rpcserver.cpp
+++ b/src/rpcserver.cpp
@@ -173,7 +173,7 @@ vector<unsigned char> ParseHexO(const UniValue& o, string strKey)
  * Note: This interface may still be subject to change.
  */
 
-string CRPCTable::help(string strCommand) const
+std::string CRPCTable::help(const std::string& strCommand) const
 {
     string strRet;
     string category;
@@ -391,7 +391,7 @@ CRPCTable::CRPCTable()
     }
 }
 
-const CRPCCommand *CRPCTable::operator[](string name) const
+const CRPCCommand *CRPCTable::operator[](const std::string& name) const
 {
     map<string, const CRPCCommand*>::const_iterator it = mapCommands.find(name);
     if (it == mapCommands.end())
@@ -1026,11 +1026,13 @@ UniValue CRPCTable::execute(const std::string &strMethod, const UniValue &params
     g_rpcSignals.PostCommand(*pcmd);
 }
 
-std::string HelpExampleCli(string methodname, string args){
+std::string HelpExampleCli(const std::string& methodname, const std::string& args)
+{
     return "> bitcoin-cli " + methodname + " " + args + "\n";
 }
 
-std::string HelpExampleRpc(string methodname, string args){
+std::string HelpExampleRpc(const std::string& methodname, const std::string& args)
+{
     return "> curl --user myusername --data-binary '{\"jsonrpc\": \"1.0\", \"id\":\"curltest\", "
         "\"method\": \"" + methodname + "\", \"params\": [" + args + "] }' -H 'content-type: text/plain;' http://127.0.0.1:8332/\n";
 }
diff --git a/src/rpcserver.h b/src/rpcserver.h
index 3f623651cc..7b462a8b79 100644
--- a/src/rpcserver.h
+++ b/src/rpcserver.h
@@ -55,7 +55,7 @@ void StopRPCThreads();
 /** Query whether RPC is running */
 bool IsRPCRunning();
 
-/** 
+/**
  * Set the RPC warmup status.  When this is done, all RPC calls will error out
  * immediately with RPC_IN_WARMUP.
  */
@@ -110,8 +110,8 @@ private:
     std::map<std::string, const CRPCCommand*> mapCommands;
 public:
     CRPCTable();
-    const CRPCCommand* operator[](std::string name) const;
-    std::string help(std::string name) const;
+    const CRPCCommand* operator[](const std::string& name) const;
+    std::string help(const std::string& name) const;
 
     /**
      * Execute a method.
@@ -142,8 +142,8 @@ extern CAmount AmountFromValue(const UniValue& value);
 extern UniValue ValueFromAmount(const CAmount& amount);
 extern double GetDifficulty(const CBlockIndex* blockindex = NULL);
 extern std::string HelpRequiringPassphrase();
-extern std::string HelpExampleCli(std::string methodname, std::string args);
-extern std::string HelpExampleRpc(std::string methodname, std::string args);
+extern std::string HelpExampleCli(const std::string& methodname, const std::string& args);
+extern std::string HelpExampleRpc(const std::string& methodname, const std::string& args);
 
 extern void EnsureWalletIsUnlocked();
 
diff --git a/src/univalue/univalue.h b/src/univalue/univalue.h
index 79018bb787..54239741e2 100644
--- a/src/univalue/univalue.h
+++ b/src/univalue/univalue.h
@@ -61,7 +61,7 @@ public:
     bool setObject();
 
     enum VType getType() const { return typ; }
-    std::string getValStr() const { return val; }
+    const std::string& getValStr() const { return val; }
     bool empty() const { return (values.size() == 0); }
 
     size_t size() const { return values.size(); }
@@ -247,4 +247,3 @@ extern const UniValue NullUniValue;
 const UniValue& find_value( const UniValue& obj, const std::string& name);
 
 #endif // BITCOIN_UNIVALUE_UNIVALUE_H
-
diff --git a/src/util.cpp b/src/util.cpp
index 33b5ee9500..da5821e530 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -702,7 +702,7 @@ boost::filesystem::path GetTempPath() {
 #endif
 }
 
-void runCommand(std::string strCommand)
+void runCommand(const std::string& strCommand)
 {
     int nErr = ::system(strCommand.c_str());
     if (nErr)
diff --git a/src/util.h b/src/util.h
index 4cc0faf4d7..6ec81698ea 100644
--- a/src/util.h
+++ b/src/util.h
@@ -126,7 +126,7 @@ boost::filesystem::path GetSpecialFolderPath(int nFolder, bool fCreate = true);
 #endif
 boost::filesystem::path GetTempPath();
 void ShrinkDebugFile();
-void runCommand(std::string strCommand);
+void runCommand(const std::string& strCommand);
 
 inline bool IsSwitchChar(char c)
 {
diff --git a/src/utilstrencodings.cpp b/src/utilstrencodings.cpp
index b10f3c5903..7d1de7d6a8 100644
--- a/src/utilstrencodings.cpp
+++ b/src/utilstrencodings.cpp
@@ -471,7 +471,7 @@ bool ParseDouble(const std::string& str, double *out)
     return endp && *endp == 0 && !errno;
 }
 
-std::string FormatParagraph(const std::string in, size_t width, size_t indent)
+std::string FormatParagraph(const std::string& in, size_t width, size_t indent)
 {
     std::stringstream out;
     size_t col = 0;
diff --git a/src/utilstrencodings.h b/src/utilstrencodings.h
index fb3ef04281..58329b51bb 100644
--- a/src/utilstrencodings.h
+++ b/src/utilstrencodings.h
@@ -88,11 +88,11 @@ inline std::string HexStr(const T& vch, bool fSpaces=false)
     return HexStr(vch.begin(), vch.end(), fSpaces);
 }
 
-/** 
+/**
  * Format a paragraph of text to a fixed width, adding spaces for
  * indentation to any added line.
  */
-std::string FormatParagraph(const std::string in, size_t width=79, size_t indent=0);
+std::string FormatParagraph(const std::string& in, size_t width = 79, size_t indent = 0);
 
 /**
  * Timing-attack-resistant comparison.
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 36baf930a5..d376f42beb 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2414,7 +2414,7 @@ set< set<CTxDestination> > CWallet::GetAddressGroupings()
     return ret;
 }
 
-set<CTxDestination> CWallet::GetAccountAddresses(string strAccount) const
+std::set<CTxDestination> CWallet::GetAccountAddresses(const std::string& strAccount) const
 {
     LOCK(cs_wallet);
     set<CTxDestination> result;
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index b0da92cfd1..2bedad3fca 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -496,7 +496,7 @@ public:
         SetNull();
     }
 
-    CWallet(std::string strWalletFileIn)
+    CWallet(const std::string& strWalletFileIn)
     {
         SetNull();
 
@@ -645,7 +645,7 @@ public:
     std::set< std::set<CTxDestination> > GetAddressGroupings();
     std::map<CTxDestination, CAmount> GetAddressBalances();
 
-    std::set<CTxDestination> GetAccountAddresses(std::string strAccount) const;
+    std::set<CTxDestination> GetAccountAddresses(const std::string& strAccount) const;
 
     isminetype IsMine(const CTxIn& txin) const;
     CAmount GetDebit(const CTxIn& txin, const isminefilter& filter) const;