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c++pointers
SirRollalot
SirRollalot

Reputation: 41

Why does incrementation of pointer or value leads to the same result in a loop

Moin Moin,

Currently I'm learning c++ and have an interesting effect which I can't explain to myself.

Why does *iterator++; also work in this situation?

From my point of view it should increase the value to the pointer of. Does this mean that the ++ operator of the returned object from std::begin(feld) is overridden to handle this to make it comfortable? I'm confused

void CArrayExamples::beginAndEndMethod()
{
    int feld[] = { 0,1,2,3,4,5,6,7,8,9 };
    
    int* iterator = std::begin(feld);
    int* ending = std::end(feld);

    while (iterator != ending)
    {
        std::cout << "iterator:" << iterator << std::endl;
        std::cout << "*iterator:" << *iterator << std::endl;
        std::cout << "ending:" << ending << std::endl;
        std::cout << "*ending:" << *ending << std::endl;
        std::cout << "-----------------------------------------------" << std::endl;

        //why does this both work? :D
        //*iterator++;
        iterator++;
        //TODO: Ask somebody!

    }
}

Upvotes: 3

Views: 71

Answers (1)

Klaus G&#252;tter
Klaus G&#252;tter

Reputation: 11977

The increment operator ++ has higher precedence than the indirection operator *, so *iterator++ is interpreted as *(iterator++), i.e. increment the iterator/pointer and return the value pointed to by the old value.

Your code does not use the returned value, though.

If you want to increment the value, not the iterator/pointer, write (*iterator)++.

Upvotes: 1

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