The following code does not work correctly. How should it be done correctly?
for (std::set<Color>::iterator i = myColorContainer.begin(); i!=myColorContainer.end(); ++i) { if ( *i == Yellow) { DoSomeProccessing( *i ); myColorContainer.erase(i); } } 
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3 Answers
Try:
for(std::set<Color>::iterator it = myColorContainer.begin(); it != myColorContainer.end();) { // note missing it++ if( (*it) == Yellow ) { DoSomeProcessing(*it); myColorContainer.erase(it++); // post increment (original sent to erase) } else { ++it; // more efficient than it++; } } 
3 Comments
Patrick
This won't work either. You should assign the return value of erase to it again.
Adrian Regan
The returned iterator is a microsoft specific implementation that breaks the standard : msdn.microsoft.com/en-us/library/8h4a3515%28VS.80%29.aspx. Sure enough, you need to increment the iterator after the erase.
scippie
This sollution is perfect if you can't use the m$-specific implementation and need to use a loop. If you don't need to use a loop, Viktor's option is even better. Thanks for a great answer. You've been a great help.
You don't need a loop as youre dealing with a set.
std::set<Color>::iterator it = myColorContainer.find(Yellow); if (it != it.myColorContainer.end()){ DoSomeProcessing(*it); myColorContainer.erase(it); } 
2 Comments
Adrian Regan
code is standards compliant. I agree @Viktor Sehr this would be the preferred way to remove an element from the set. However, the question asks how to get the code snippet to work.
Viktor Sehr
@daramarak:I think you answered while I edited the code (thought it was a std::vector in my first post)
for (std::set<Color>::iterator i = myColorContainer.begin(); i!=myColorContainer.end(); /* No i++ */) { if ( *i == Yellow) { DoSomeProccessing( *i ); std::set<Color>::iterator tmp = i; ++i; myColorContainer.erase(tmp); } else { ++i; } } Once you go to next message with ++i it is guaranteed to be valid - property of std::set that iterators on inserted elements are never invalidated unless the element is removed.
So now you can safely erase previous entry.
