Using find_if on std::vector with bind2nd and string::compare?

One option is to cast the member function pointer to suitable type. Another thing you are forgetting is that std::string::compare returns 0 for equal strings, so you'll also need to negate the functor. All in all: std::find_if( vec.begin(), vec.end(), std::not1( std::bind2nd( std::mem_fun_ref(static_cast(&std::string::compare)), "findme" ) ) ) As to your rationale against boost: its templates are an order of a magnitude more flexible than what you can find in STL functional header.It's either boost, you wait for C++0x lambdas (which I believe will be the preferable way in such situations) or you write some helpers yourself.

Currently it can't get simpler than: std::find_if(vec.begin(), vec.end(), boost::bind(&X::name, _1) == "findme") FYI, C++0x will add std::bind which is similar to boost::bind but it seems the convenience of overloaded operator== will not be there.

One option is to cast the member function pointer to suitable type. Another thing you are forgetting is that std::string::compare returns 0 for equal strings, so you'll also need to negate the functor. All in all: std::find_if( vec.begin(), vec.end(), std::not1( std::bind2nd( std::mem_fun_ref(static_cast(&std::string::compare)), "findme" ) ) ); As to your rationale against boost: its templates are an order of a magnitude more flexible than what you can find in STL functional header.It's either boost, you wait for C++0x lambdas (which I believe will be the preferable way in such situations) or you write some helpers yourself.

Currently it can't get simpler than: std::find_if(vec.begin(), vec.end(), boost::bind(&X::name, _1) == "findme"); FYI, C++0x will add std::bind which is similar to boost::bind but it seems the convenience of overloaded operator== will not be there.

1 This doesn't compile! Reference to reference problem. – TimW Sep 4 '09 at 13:49 Right, not with VC++ (OK for MinGW and Comeau online).

I changed to use a different overload which shouldn't exhibit the same problem. (I guess the question is really about what to do in precence of overloads and not specifically how to find a string with find_if and string::compare - which is just stupid, as should be clear. ) – UncleBens Sep 4 '09 at 14:30 One more thing, the presence of overloads is just as much of a problem for boost::bind etc, unless there happens to be another way (such as in this case, using operator== instead of compare).

– UncleBens Sep 4 '09 at 14:33.

Select the correct overload yourself. Int (string::*compare)(const string&) const; compare = &string::compare; find_if(s.begin(), s.end(), bind2nd( mem_fun_ref(compare), string("findme"))); But then you get stuck with the reference to reference problem "Item #50 of Effective STL". And the boost.

Bind lib or boost. Lambda is the solution for that. Int (string::*compare)(const string&) const; compare = &string::compare; find_if(s.begin(), s.end(), bind(compare, _1, "findme")==0); Or find_if(s.begin(), s.end(), bind2nd(std::equal_to(), string("findme"))).

I think you will find that the syntax rapidly gets unweildy, if you are trying to call several functions together. Did you try something like this? Find_if(s.begin(), s.end(), bind2nd(mem_fun_ref(&string::compare), "findme")); Does this not match the char * overload?

The problem really lies in the expression mem_fun_ref(&string::compare). How do you pass a overloadset of functions to mem_fun_ref? – MSalters Sep 4 '09 at 13:16 Yes, I tried this, and no, it does not match.

– fuenfundachtzig Sep 6 '09 at 13:54.

If a function has overloaded functions, you can cast the function to correct signature like (void (*)(int,int))(&f). For your second question, if you use boost, you can do something like this, find_if(s.begin(), s.end(), boost::bind(std::equal_to(), boost::bind(&SomeClass::name, _1), name).

1 boost::bind overloads a few operators for convenience, so the "equal_to" par of your example can be replaced by using operator==: boost::bind(&SomeClass::name, _1) == name which is more readable – Éric Malenfant Sep 4 '09 at 13:01 I thought that was only in boost::lambda. I agree it is more readable in this case, but I was just trying to demonstrate how to use boost::bind – leiz Sep 4 '09 at 13:25 The original version of boost::bind did not have those operator overloads, but "recent" (from 1.33) versions have: boost. Org/doc/libs/1_40_0/libs/bind/bind.

Html#operators – Éric Malenfant Sep 4 '09 at 14:14.

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