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c++coding-stylefor-loopiterator

Iterate through a C++ Vector using a 'for' loop


I am new to the C++ language. I have been starting to use vectors, and have noticed that in all of the code I see to iterate though a vector via indices, the first parameter of the for loop is always something based on the vector. In Java I might do something like this with an ArrayList:

for(int i=0; i < vector.size(); i++){
   vector[i].doSomething();
}

Is there a reason I don't see this in C++? Is it bad practice?


Solution

  • Is there any reason I don't see this in C++? Is it bad practice?

    No. It is not a bad practice, but the following approach renders your code certain flexibility.

    Usually, pre-C++11 the code for iterating over container elements uses iterators, something like:

    std::vector<int>::iterator it = vector.begin();
    

    This is because it makes the code more flexible.

    All standard library containers support and provide iterators. If at a later point of development you need to switch to another container, then this code does not need to be changed.

    Note: Writing code which works with every possible standard library container is not as easy as it might seem to be.