How to check if my iterator stands on nothing

Question

Hello, i'm using a multimap stl, i iterate my map and i did'nt find the object i wanted inside the map, now i want to check if my iterator holds the thing i wanted or not and i'm having difficulties with it because it's not null or something. thanx!

Answer 1

If it doesn't find the thing you want then it should equal the iterator returned by the end() method of the container.

So:

iterator it = container.find(something);
if (it == container.end())
{
  //not found
  return;
}
//else found

Answer 2

Why are you iterating over your map to find something, you should go like ChrisW to find a key in your map...

Mmm, are you trying to find the value in your map and not the key? Then you should do:

map<int, string> myMap;
myMap[1] = "one"; myMap[2] = "two"; // etc.

// Now let's search for the "two" value
map<int, string>::iterator it;
for( it = myMap.begin(); it != myMap.end(); ++ it ) {
   if ( it->second == "two" ) {
      // we found it, it's over!!! (you could also deal with the founded value here)
      break; 
   }
}
// now we test if we found it
if ( it != myMap.end() ) {
   // you also could put some code to deal with the value you founded here,
   // the value is in "it->second" and the key is in "it->first"
}