A Simple Example of rP-XML at Work

The following example shows how easy it is to add XML Persistence to your classes, using rP-XML.

In this example, we create a hypothetical employee class which can be stored in XML.

All persistence-related code is shown in blue highlight:

#include <stdio.h>

#include "xmlpersist.h"

class Employee : public XMLPersistent
{
public:
	char*	m_pszName;
	int	m_iEmployeeNumber;
	int	m_iDepartment;
	char*	m_pszResume;

	Employee()
	{
		m_pszName = NULL;
		m_iEmployeeNumber = 0;
		m_iDepartment = 0;
		m_pszResume = NULL;
	}

	~Employee()
	{
		DeleteDynamicString(m_pszName);
		DeleteDynamicString(m_pszResume);
	}

	DECLARE_XMLPERSIST_CLASS;
};

// The following is the "data exchange macro block".
// It describes the mapping between members of the Employee class
//  and an XML tag we have chosen to call employee
BEGIN_XMLPERSIST_CLASS(Employee,employee)
	XMLPERSIST_ITEM(m_pszName,name)
	XMLPERSIST_ITEM(m_iEmployeeNumber,employee-number)
	XMLPERSIST_ITEM(m_iDepartment,department)
BEGIN_XMLPERSIST_CONTENTS
	XMLPERSIST_CONTENTS(m_pszResume)
END_XMLPERSIST

main(int argc, char* argv[])
{
	Employee anEmployee;

	XMLStorage xmlObject;

	if (!xmlObject.ReadFile(&anEmployee, argv[1]))
	{
		printf ("read file failed: error code = %d;\nmessage = %s\n",
			xmlObject.m_Exception.m_Code,
			xmlObject.m_Exception.Message());
	}

	printf ("Employee Name: %s\nEmployee Number: %d\nDepartment: %d\nResume:\n%s\n",
		anEmployee.m_pszName, anEmployee.m_iEmployeeNumber, anEmployee.m_iDepartment,
		anEmployee.m_pszResume);

	XMLPersistent::SetDynamicString(anEmployee.m_pszName, "John Smith");
	anEmployee.m_iEmployeeNumber = 101;
	anEmployee.m_iDepartment = 10;

	XMLPersistent::SetDynamicString(anEmployee.m_pszResume,
		"Resume of John Smith\n",
		"Contact Information...\n"
		"Career Summary...\n"
		"Work History...\n"
		"Education...\n"
		"Interests...\n"
		);

	if (!xmlObject.WriteFile(&anEmployee, argv[1]))
	{
		printf ("write file failed: error code = %d; message = %s\n",
			xmlObject.m_Exception.m_Code,
			xmlObject.m_Exception.Message());
	}
}

If you were to build and run the above example, giving the name of a non-existent file, you would get the following results:

Written to a file as named on the command line:

Written to standard output:

<employee name="John Smith"
 employee-number="101"
 department="10">
Resume of John Smith
Contact Information...
Career Summary...
Work History...
Education...
Interests...
</employee>

read file failed: error code = 11; 
message = Failed to open filename. No such file or directory
Employee Name: 
Employee Number: 0
Department: 0
Resume:

Note: the actual XML file may not appear exactly as shown; newlines have been added for clarity.

If you were to re-run the example, giving the name of the file which was just created, you would get the following results:

Written to a file as named on the command line:

Written to standard output:

<employee name="John Smith"
 employee-number="101"
 department="10">
Resume of John Smith
Contact Information...
Career Summary...
Work History...
Education...
Interests...
</employee>

Employee Name: John Smith
Employee Number: 101
Department: 10
Resume:
Resume of John Smith
Contact Information...
Career Summary...
Work History...
Education...
Interests...