COMP2004 Programming Practice
2002 Summer School

Week 4 Wednesday Tutorial Exercises

  1. The sum.h file contains the sum() template function from today's lecture, and the file contains the tests of sum() from today's lecture. Compile the file and observe it crash. Modify the sum() function so that it works by taking a constant reference to the object which should be considered "zero" for the purposes of the summation. In particular, make the function definition be
    template <typename T>
    T sum(const vector<T> &v, const T &zero = 0);
    and then make the local variable result be initialised to the value of zero. Notice that the default value for zero means that sum() can still be called in the same way as before the modification. Compile and run and notice that it still crashes. Now modify so that sum(vs) is instead sum(vs, string()). Compile and run and verify that it now works.

  2. Modify your List class from last Wednesday's tutorial so that it is a fully templated class which can be used to store values of any type. Also modify the test program so that it tests the List class with at least two different types.

  3. Implement some template functions that use iterators and containers (similar to the final version of the find() function from today's lecture) and check that they work with the different containers looked at in the lectures. For example:

  4. Write a simple Array template class. It should be a simple wrapper around normal C++ style arrays, but it should also keep track of the size of the array and return the size with a size() method. It shouldn't do any bounds-checking, that is, there is no need to check whether or not an element being accessed is valid (ie. between 0 and size() - 1) or not. To allow the Array objects to use indexing as for normal C++ arrays, you should use the operator[] which can be defined as followed:
    T &operator[](size_t i);
    and should return a reference to the i-th element of the Array object.

    Your class should be usable as follows:

    #include "Array.h"
    #include <iostream>
    int main() {
    	Array<int> a(10);
    	for (int i = 0; i < a.size(); i++)
    		a[i] = i + 1;
    	Array<int> b = a;
    	for (int i = 0; i < a.size(); i++)
    		b[i] *= 2;
    	for (int i = 0; i < a.size(); i++)
    		std::cout << a[i] << " " << b[i] << std::endl;
    	Array<const char*> s(3);
    	s[0] = "one";
    	s[1] = "two";
    	s[2] = "three";
    	for (int i = 0; i < s.size(); i++)
    		std::cout << s[i] << std::endl;