Can you check what is wrong with this code

Header file

Code:

#ifndef STRING_HPP
#define STRING_HPP

#include <iostream>

using namespace std;

/* mystring class */
class mystring
{
    public:

    typedef struct STRING* String;

     /*String struct */
    struct STRING
    {
        int size;
        char *theString;
    };




void validateString( mystring& theString );

mystring()
{
	String->theString = NULL;
	String->size =0;
}
mystring( const char *init)
{
	newString( init );
}

~mystring(mystring& theString)
{
	destroyString( theString );
}
mystring&  destroyString( mystring& theString );
mystring& newString( char* theString );
char* charAt(  mystring& theString, int index );
void printString( mystring& theString);
friend mystring& operator+(  mystring& string1,  mystring& string2 );

};



#endif

Function file

Code:

#include <iostream.h>

#include <assert.h>
#include "mystring.hpp"
using namespace std;

int stringCount = 0; /*Keep track of string count */
/*------------------------------------------------------
 newString

 PURPOSE: Create a new string struct
 INPUT PARAMETERS:input string
 OUTPUT PARAMETERS: string object
------------------------------------------------------ */

mystring& mystring::newString( const char* init )
{
  String *newString = NULL;

  assert( init != NULL );

  newString = new String[init];
  assert( newString != NULL );

  if ( newString != NULL )
  {
    newString->theString = new char( strlen(init) + 1 ); /*Assign array size of the new string object*/
    assert( newString -> theString != NULL );

    if ( newString -> theString != NULL )
    {
      strcpy( newString -> theString, init );/*Copy input string to string component of the struct */
      newString -> size = strlen( newString -> theString );/*Assign size of the String object */

      assert( newString -> size == strlen( init ) );

      stringCount++;
    }

    else
    {
      delete newString ;
      newString = NULL;
    }
  }

  return( newString );
}

/*------------------------------------------------------
 validateString

 PURPOSE: To check if there is any content in the object or empty object */
 INPUT PARAMETERS:string object
 OUTPUT PARAMETERS: void
------------------------------------------------------ */

 void mystring::validateString(  mystring& theString )
{
  assert( theString != NULL );
  assert( theString -> theString != NULL );
  assert( theString -> theString[theString -> size] == '\0' );
}

/*------------------------------------------------------
 destroyString

 PURPOSE: Destroys the string struct
 INPUT PARAMETERS:string object
 OUTPUT PARAMETERS: string object
------------------------------------------------------ */

mystring& mystring::destroyString( mystring& theString )
{
  validateString( theString );
  assert( stringCount > 0 );

  delete theString -> theString ; /*Delete String component of the struct */
  delete theString ; /*Delete the object itself */
  theString = NULL;

  stringCount--;

  return( theString );
}


char* mystring::charAt(  mystring& theString, int index )
{
  validateString( theString );
  assert( index >= 0 );
  assert( index < theString -> size );

  return( theString -> theString[index] );
}

/*------------------------------------------------------
 operator+
 PURPOSE: Operator overloading of the operator +
 INPUT PARAMETERS:string object
 OUTPUT PARAMETERS: new string object which has contents of string1 and 2
------------------------------------------------------ */

mystring& mystring::operator+(   mystring& string1, mystring& string2 )
{
  String *newString = NULL;

  validateString( string2 );

  newString = new String[];
  assert( newString != NULL );

  if ( newString != NULL )
  {
    newString -> size = this. size + string2 -> size;
    newString -> theString = new char [newString -> size + 1];
    assert( newString -> theString != NULL );

    if ( newString -> theString != NULL )
    {
      strcpy( newString -> theString, string1 -> theString );
      strcpy( &(newString -> theString[string1 -> size]), string2 -> theString );

      assert( newString -> size == strlen( newString -> theString ) );
      assert( newString -> theString[0] == this. theString[0] );
      assert( newString -> theString[this. size] == string2 -> theString[0] );

      stringCount++;
    }

    else
    {
      delete newString ;
      newString = NULL;
    }
  }

  return( newString );
}

/*------------------------------------------------------
 printString

 PURPOSE: Print the contents of the string object
 INPUT PARAMETERS: string onject
 OUTPUT PARAMETERS: void
------------------------------------------------------ */

void mystring::printString(  mystring& theString )
{
  validateString( theString );

  cout << theString->size<<endl;
  cout << theString -> theString << endl ;
}

Can you tell us if it's getting a compile error or if there is a specific run time error?

IM getting a long list of compile erros

Errors

Code:

mystring.hpp:49: error: destructors may not have parameters
mystring.hpp: In constructor `mystring::mystring()':
mystring.hpp:40: error: expected primary-expression before '->' token
mystring.hpp:41: error: expected primary-expression before '->' token
mystring.hpp: In constructor `mystring::mystring(const char*)':
mystring.hpp:45: error: invalid conversion from `const char*' to `char*'
mystring.hpp:45: error:   initializing argument 1 of `mystring& mystring::newString(char*)'
mystring.hpp: In destructor `mystring::~mystring()':
mystring.hpp:50: error: `theString' undeclared (first use this function)
mystring.hpp:50: error: (Each undeclared identifier is reported only once for each function it appears in.)
mystring.cpp: At global scope:
mystring.cpp:27: error: prototype for `mystring& mystring::newString(const char*)' does not match any in class `mystring'
mystring.hpp:53: error: candidate is: mystring& mystring::newString(char*)
mystring.cpp: In member function `mystring& mystring::newString(const char*)':
mystring.cpp:32: error: expression in new-declarator must have integral or enumeration type
mystring.cpp:37: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:38: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:40: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:42: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:43: error: request for member `size' in `*newString', which is of non-class type `STRING*'
mystring.cpp:43: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:45: error: request for member `size' in `*newString', which is of non-class type `STRING*'
mystring.cpp:57: error: invalid initialization of reference of type 'mystring&' from expression of type 'STRING**'
mystring.cpp: At global scope:
mystring.cpp:64: error: `INPUT' does not name a type
mystring.cpp: In member function `mystring& mystring::destroyString(mystring&)':
mystring.cpp:88: error: base operand of `->' has non-pointer type `mystring'
mystring.cpp:89: error: type `class mystring' argument given to `delete', expected pointer
mystring.cpp: In member function `char* mystring::charAt(mystring&, int)':
mystring.cpp:102: error: base operand of `->' has non-pointer type `mystring'
mystring.cpp:104: error: base operand of `->' has non-pointer type `mystring'
mystring.cpp: In member function `mystring& mystring::operator+(mystring&)':
mystring.cpp:120: error: expected primary-expression before ']' token
mystring.cpp:125: error: request for member `size' in `*newString', which is of non-class type `STRING*'
mystring.cpp:125: error: request for member `size' in `this', which is of non-class type `mystring* const'
mystring.cpp:125: error: base operand of `->' has non-pointer type `mystring'
mystring.cpp:126: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:126: error: request for member `size' in `*newString', which is of non-class type `STRING*'
mystring.cpp:127: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:129: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:131: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:131: error: `string1' undeclared (first use this function)
mystring.cpp:132: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:132: error: base operand of `->' has non-pointer type `mystring'
mystring.cpp:134: error: request for member `size' in `*newString', which is of non-class type `STRING*'
mystring.cpp:134: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:135: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:135: error: request for member `theString' in `this', which is of non-class type `mystring* const'
mystring.cpp:136: error: request for member `theString' in `*newString', which is of non-class type `STRING*'
mystring.cpp:136: error: request for member `size' in `this', which is of non-class type `mystring* const'
mystring.cpp:136: error: base operand of `->' has non-pointer type `mystring'
mystring.cpp:148: error: invalid initialization of reference of type 'mystring&' from expression of type 'STRING**'
mystring.cpp: In member function `void mystring::printString(mystring&)':
mystring.cpp:163: error: base operand of `->' has non-pointer type `mystring'
mystring.cpp:164: error: base operand of `->' has non-pointer type `mystring'
*** Error code 1
make: Fatal error: Command failed for target `mystring.o'

Well you'll have to start going through them - first one is obvious enough - you destructor should not take parameters. Secondly, your class actually has no data members - only a typedef and a struct definition. Thirdly your class doesn't contain member function prototypes which you later try to define as being in the class. These are rather serious mistakes and they're only the tip of the iceberg - I'd suggest that you go back and read all the tutorials before you continue, or try those at www.cplusplus.com