title: malloc: *** error for object 0x10020a2c0: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug
body: <p>My rest of the program is working fine except when I try to use the += operator in the main, it throws an error.Assignment 4(1643,0x10013c3c0) malloc: <strong>* error for object 0x10020a2c0: pointer being freed was not allocated
  *</strong> set a breakpoint in malloc_error_break to debug.
   Any help of how to fix it will be appreciated. 
  This is the definition of my += function:</p>
  
  <pre><code>Student Student::operator+=(string item){
  CheckOut(item);  //checkout is a member function of the class Student
  return *this;
  </code></pre>
  
  <p>}</p>
  
  <p>This is where the xcode compiler points the error at saying thread1: signal SIGABRT. I dont know what this error means.</p>
  
  <pre><code>Student::~Student(){
  delete [] pointer; //it points error right here
  pointer = NULL;
  </code></pre>
  
  <p>}</p>