String class: Index characters and '=' operator

 

#include <iostream>
#include <cstring>
#include <cstdlib>
using namespace std;

class StringClass {
  char *p;
  int len;
public:
  StringClass(char *s);
  ~StringClass() { 
     cout << "Freeing " << (unsigned) p << '\n';
     delete [] p;
   }
  char *get() { return p; }
  StringClass &operator=(StringClass &ob);
  char &operator[](int i);
};

StringClass::StringClass(char *s)
{
  int l;

  l = strlen(s)+1;

  p = new char [l];
  if(!p) {
    cout << "Allocation error\n";
    exit(1);
  }

  len = l;
  strcpy(p, s);
}

// = operator
StringClass &StringClass::operator=(StringClass &ob)
{
  // see if more memory is needed
  if(len < ob.len) { // need to allocate more memory
    delete [] p;
    p = new char [ob.len];
    if(!p) {
      cout << "Allocation error\n";
      exit(1);
    }
  }
  len = ob.len;
  strcpy(p, ob.p);
  return *this;
}  

// 
char &StringClass::operator[](int i)
{
  if(i <0 || i>len-1) {
    cout << "\nIndex value of ";
    cout << i << " is out-of-bounds.\n";
    exit(1);
  }
  return p[ i ];
}

int main()
{
  StringClass a("Hello"), b("There");

  cout << a.get() << '\n';
  cout << b.get() << '\n';

  a = b; // now p is not overwritten

  cout << a.get() << '\n';
  cout << b.get() << '\n';

  cout << a[0] << a[1] << a[2] << endl;

  a[0] = 'X';
  a[1] = 'Y';
  a[2] = 'Z';

  cout << a.get() << endl;

  return 0;
}

Related examples in the same category

1.	Operator overload: new, delete, new[] and delete[]
2.	Define operator []
3.	Overload [].
4.	Return a reference from [].
5.	Index operator for class

String class: Index characters and '=' operator : Index « Overload « C++

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