Exercise "generic list"

• Generic list container (to be used later in the course, perhaps)

Tasks

1. Build a simple class that implements a generic list (a list that can hold items of any given type (all items must be of the same type though)). The list must be able to grow, that is, it must be possible to add items to the list.

   Basically only one method, "add", is needed. Something like
   #ifndef HAVE_GENLIST_H #define HAVE_GENLIST_H #include <stddef.h> #include <stdlib.h> #include <assert.h> #include <iostream> #define SELF (*this) #define FOR(i) for(int i=0;i<Size;i++) template < typename T > class genlist { private: int Size; T *data; /* C-array */ public : const int& size=Size; T& operator[](int i){ assert(i >= 0 && i < Size); return data[i]; } genlist() { /* default ctor */ data = nullptr; Size = 0; } genlist(genlist& other){ /* copy ctor */ Size=other.size; data = new T[Size](); FOR(i) SELF[i]=other[i]; } genlist(genlist&&) = delete; /* move ctor */ ~genlist() { /* dtor */ delete[] data; Size = 0; } genlist& operator=(genlist& other){ /* copy assignment */ SELF.~genlist(); Size=other.size; data = new T[Size](); FOR(i) SELF[i]=other[i]; return SELF; } genlist& operator=(genlist&&) = delete; /* move assignment */ void add(T item) { T *newdata = new T[Size+1](); FOR(i)newdata[i]=data[i]; newdata[Size] = item; Size++; delete[] data; data=newdata; } }; #endif

   Suppose you have an input file with a table of numbers separated by blanks and/or tabs, like this

   129.24 24.8             4.847
   		88.6   33.745 7.78
   30.39  99.811              6.723
       -1.33   96.3   2.23
   

   Create a Main function that reads such a table line by line from the standard input into a genlist<std::vector<double>> and then prints the numbers in the form of a neat table into standard output in exponential format. Something like
   #include"genlist.h" #include<iostream> #include<sstream> #include<iomanip> #include<string> #include<vector> int main(){ genlist<std::vector<double>> list; std::string line; double x; while(std::getline(std::cin,line)){ std::istringstream iss(line); std::vector<double> numbers; while(iss >> x) numbers.push_back(x); list.add(numbers); } for(int i=0;i<list.size;i++){ std::cout << "list[" << std::setw(2) << i << "]="; for(double x: list[i]) std::cout << " " << std::scientific << std::setprecision(4) << x; std::cout << "\n"; } /* never mind the following... */ genlist<genlist<double>> dlist; genlist<double> d1; d1.add(5.4e-2); dlist.add(d1); d1.add(6.7e8); dlist.add(d1); d1.add(0.99); dlist.add(d1); std::cout << "dlist=" << std::endl; for(int i=0;i<dlist.size;i++){ for(int j=0;j<dlist[i].size;j++) std::cout << dlist[i][j] << " "; std::cout << std::endl; } return 0; }//main

2. (Extra) Implement "void remove(int i)" method that removes element number "i".

3. (Extra) Improve the speed of the "add" method by increasing the capacity of the data-array not by one element, but instead by doubling it. That should decrease the amount of array copying significantly for the price of increased memory usage.

4. (Extra) Implement generic list using a chain of nodes.