Please someone tell me how to allocate memory to an integer array dynamically without specifying it's size (i.e.not arr [5])

Question

the size of an array must be known only at runtime( should depend on user). I tried out this
while(cin>>n)
{
arr [i++]=n;
}
but I don't think that the above code is correct please if someone finds the correct ping me so that let me know. thank you

Answer 1

Your best bet would be using the vector template class. It can grow or shrink as needed.
http://en.cppreference.com/w/cpp/container/vector

Answer 2

Also it would be much helpful if you provide some other better solution

Answer 3

you need to know how big the array must be, so you can allocate the memory needed for it. so your user could for example input a size n and you could use malloc to allocate the appropriate size(i‘m assuming we are talking about c in c++ you of course have to use new). you can not dynamically change the size of an array. if you need that you should use a linked list or another datastructure that can handle dynamic changes of size.
so in c++ for example you can do:
cin >>n;
int *array = new int[n];
to create an array of user specified size
if you do not want to specify a size on creation you can use vector or similar datastructures in c++

Answer 4

i dont know c++ but could you use an arraylist.
in java an arraylist is an array class where if it runs out of space it creates a new array that is twice as big and “copies” the values from the old array to the new array in order. thus it has more space
i dont know if that translates to c++ and if it does it still may not work in this case

Answer 5

thank you so much for all those who replied me.