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iterator trouble

Started by Mike.Popoloski Apr 14, 2006 at 7:02 PM 3 replies 950+ views

Original Post

197

Apr 14, 2006 at 7:02 PM

I am having a little trouble with my vector and deleting items from it. For my vector, I am using this: std::vector structs; Now, I want to loop through each member of the vector and erase each one that has a certain member variable set. This is what I have so far:


std::vector<STRUCT*>::iterator i;
for( i = structs.begin(); i != structs.end(); i++ )
{
   if( ( *i )->bShouldBeCleared )
      structs.erase( i );
}

Now, whenever I run this code, my debugger yells at me every time it hits the 4th line, something along the lines of invalid pointer access. Am I able to do what I am doing? I am quite sure that the objects that the vector is pointing to do exist. Thanks

Fruny

203

Fruny

Apr 14, 2006 at 7:12 PM

erase() invalidates iterators. Once you're erased i, you can't increment it. Use the return value from erase.

gumpy

Apr 14, 2006 at 7:18 PM

my last post happens to be an example of erasing elements while iterating through a container.

jflanglois

Apr 14, 2006 at 7:25 PM

Or use std::remove_if/vector::erase:

bool shouldClear( STRUCT *s ) {  return s->bShouldBeCleared();}// ...structs.erase( std::remove_if( structs.begin(), structs.end(), shouldClear ), structs.end() );

[edit] Make sure that you actually delete the pointers if you have newed them. Erasing them from an STL container will not delete them from memory.

jfl.

Mike.Popoloski

Author

197

Mike.Popoloski

Apr 14, 2006 at 8:18 PM

Quote:
erase() invalidates iterators. Once you're erased i, you can't increment it. Use the return value from erase.

Ah! That would be it. Thanks again.

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