CODEWITHSUNDEEP
c++iterator
chriskirk
chriskirk

Reputation: 761

C++ simple iterator implementation

I have arrays like:

template<class T> class F
{
   ...
   bool isSet() { return set_; }
   T& GetVal() { return val_; }

private:
   T val_;
   bool set_; 
   ...
}

F<S1> arr1[10];

I'm looking for an iterator (or iterator-like class) to simplify the following:

F<S1>* cur = arr1[0];
while(cur.IsSet())
{
   S1* ptr = cur->GetVal();
   // do something with ptr
   cur++;
};

Would like something a bit cleaner that can work with different types S1, S2, etc..

Upvotes: 1

Views: 1403

Answers (3)

Joel Falcou
Joel Falcou

Reputation: 6357

you can make your own iterator using the Boost Iterator library, especially iterator_facade

http://www.boost.org/doc/libs/1_49_0/libs/iterator/doc/iterator_facade.html

Upvotes: 3

Open AI - Opting Out
Open AI - Opting Out

Reputation: 24133

Really you're looping until you find an F which isn't set.

Use std::find_if:

#include <algorithm>
#include <iterator>

template<typename Type>
bool doSomethingOrStopIfNotSet(F<Type>& object)
{
    const bool isSet = object.isSet(); 
    if(isSet)
    {
        // do something
    }
    return !isSet; // return false so that find_if keeps looking
}

int main()
{
    F<int> arr[100];
    std::find_if(std::begin(arr), std::end(arr), doSomethingOrStopIfNotSet<int>);
}

Upvotes: 2

Kerrek SB
Kerrek SB

Reputation: 476950

The standard provides iterators for arrays:

#include <iterator>

T arr[100];

for (auto it = std::begin(arr), end = std::end(arr); it != end; ++it)
{
    foo(*it);
    it->zap();
}

The type of it will just be T *, but this gives you a uniform interface.

The term "iterator" really just refers to a concept rather than any particular piece of code. Naked pointers are perfectly legitimate iterators. What matters is that std::iterator_traits gives the correct typedefs, which it does for naked pointers.

Upvotes: 8

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