Expanding Array

[mekkatorqu]

Hello,

how can I expand array?

for example let's say I have array with 3 elements

int a[3] = {1, 5, 10};

how can I expand him to 5 elements but make him still contain his parameters?

same with 2 dimensional array (I hope it is called "dimension")

and array that looks like this:

int a[3][2] = {1 {1,2}, 2 {2,3}, 3{3,4}}

or simply, how can I make array that will have 3 elements, and each of those elements will have 2 elements, and how can I define values of those elements when creating array

[Moschops]

You must create a new array of the size you want and copy the elements of the old array into it.

[Gaminic]

An "expanding array" is called a vector, and an implementation is available in the STL (include the <vector> header).

A vector allows array-like accessing (myVec[3], just like you would do myArray[3]) as well as "expanding", either in a controlled way (myVec.resize(newSize)) and in an incremental way (myVec.push_back(newItem), which adds an extra item to the end of the vector, effectively increasing its size by 1).

Do keep in mind that while a vector supports this behaviour, it's not cheaper than your own implementation [maybe somewhat, because the implementation is done by people much smarter than you and I]. Changing the size of a vector still means a new array has to be created and all elements have to be copied into it. Just because it's hidden doesn't mean you don't pay the cost.