Well,you can create a dynamic array and gives it any size that you want while the program is running.
Here is an example of it.
#include <iostream.h>
void main()
{
float *array;
int size;
cout<<"\t\tStoring data in an array."<<endl<<endl;
cout<<"How long will be your array ?"<<endl;
cin>>size;
array = new float[size]; // allocating memory to the array
for( int i = 0; i < size; i++ )
{
cout<<"array["<<i<<"] = ";
cin>>array;
}
cout<<"This new array have been created !"<<endl;
cout<<"array["<<size<<"] = {";
for( i = 0; i < size; i++ )
{
cout<<array;
if( i < size - 1 )
cout<<",";
}
cout<<"} ";
delete array; // freeing memory
}