Re: adding search capability to a Vector

From:
SG <s.gesemann@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Mon, 9 Feb 2009 01:30:40 -0800 (PST)
Message-ID:
<527ba897-bd47-4111-88c0-bb1ac2ac47be@h20g2000yqn.googlegroups.com>
On 9 Feb., 09:55, Kei <k7m...@gmail.com> wrote:

I am trying to add a simple search behaviour to a STL Vector like the
following:

//---- declaration ---

typedef struct {
        std::string name;
        std::string favouriteFood;} TBuddy;


This struct isn't C compatible anyway so you might want to define it
the C++ way:

  struct TBuddy {
    //...
  };

typedef TBuddy* PBuddy;


Why do you want to store pointers in the vector?

class TBuddies: public std::vector<PBuddy> {
public:
        std::string favouriteFoodOf(const std::string& name) cons=

t;

};


Why public inheritance? Why making your own class?
Use std::find_if that is defined in <algorithm>
http://www.cplusplus.com/reference/algorithm/find_if.html

//---- implementation ---

std::string TBuddies::findValue(const std::string& name) const
{
        for(TBuddies::iterator i= this->begin(); i!= this->en=

d(); ++i) {

                PBuddy b = *i;
                if(b->name ==s) return b->favouriteFo=

od;

        }
        return "";
}


Since the member function is declared const, 'this' points to a const
TBuddies object. The functions begin() and end() are "const
overloaded". Their const versions return instances of const_iterator.

Anyways, inside findValue you don't need access to any protected
fields. You better make it a free function that calles std::find_if.

Or better yet: use a std::map. It looks like std::map (instead of
std::vector) is what you are looking for.

Cheers!
SG

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