Home-made string class constructor

**aab19902** · 03-10-2009

I have to construct a class for strings. C++ already has one, but my assignment is a home-made version. I am very lost as to how to make the constructor work. I have toyed with a few things, but I was given a header file to follow and I have no clue what to do. Any help would be appreciated.

Code:

class String
{
  private:

    unsigned Capacity;  // Number of memory locations reserved
    unsigned Length;    // Number of memory locations in use
    char * Mem;         // Pointer to memory to hold characters

  public:

    // Construct empty string
    //
    String()
    {
      Mem = NULL;
      Capacity = 0;
      Length = 0;
    }

I am clueless as to what to do. The constructor seems to be giving me the most trouble, I am not even sure where to start. All the other parts of the assignment seem possible, but the constructor is confusing me with the Capacity, Length, and * Mem.

Please help with comments, explanations, example code, or anything you think that would be helpful.

**tabstop** · 03-10-2009

Other than the fact that you've already written it, what's confusing to you? The point of a constructor is to make sure each member variable has a meaningful value. For instance, if a char * was passed into a(nother) constructor, you could use the data pointed to to determine the length, allocate some memory into Mem and copy the string over, and set the capacity appropriately.