Safer std::vector indexing.

samples/exiv2json.cpp

@@ -74,7 +74,7 @@ bool getToken(std::string& in, Token& token, std::set<std::string>* pNS = nullpt
 
     while ( !result && in.length() ) {
         std::string c = in.substr(0,1);
-        char        C = c[0];
+        char        C = c.at(0);
         in            = in.substr(1,std::string::npos);
         if ( in.length() == 0 && C != ']' ) token.n += c;
         if ( C == '/' || C == '[' || C == ':' || C == '.' || C == ']' || in.length() == 0 ) {
@@ -115,7 +115,7 @@ Jzon::Node& addToTree(Jzon::Node& r1, const Token& token)
 
 Jzon::Node& recursivelyBuildTree(Jzon::Node& root,Tokens& tokens,size_t k)
 {
-    return addToTree( k==0 ? root : recursivelyBuildTree(root,tokens,k-1), tokens[k] );
+    return addToTree( k==0 ? root : recursivelyBuildTree(root,tokens,k-1), tokens.at(k) );
 }
 
 // build the json tree for this key.  return location and discover the name
@@ -128,7 +128,7 @@ Jzon::Node& objectForKey(const std::string& Key, Jzon::Object& root, std::string
     std::string input  = Key ; // Example: "XMP.xmp.MP.RegionInfo/MPRI:Regions[1]/MPReg:Rectangle"
     while ( getToken(input,token,pNS) ) tokens.push_back(token);
     size_t      l      = tokens.size()-1; // leave leaf name to push()
-    name               = tokens[l].n ;
+    name               = tokens.at(l).n ;
 
     // The second token.  For example: XMP.dc is a namespace
     if ( pNS && tokens.size() > 1 ) pNS->insert(tokens[1].n);