1

Command Processor VSaving Changes

Command Processor

We need to be able to save changes to the database that result from user actions.

Download example from last class http://www.cse.usf.edu/~turnerr/Object_Oriented_Design/Dow

nloads/2011_04_11_Command_Processor_4/ File Geography_with_getline.zip

2

3

Saving Changes

The DOM can output itself to a file. Requires updating the DOM.

Easier to work with our own objects. Add code to output XML.

http://www.cse.usf.edu/~turnerr/Object_Oriented_Design/Downloads/2011_04_13_Saving_Changes/ File output_XML.cpp

Add to Command_Processor.cpp3

4

Command_Processor.cpp

void Command_Processor::Output_XML()

{

ofstream outfile;

string output_file_name = "states2.xml";

outfile.open(output_file_name.c_str());

if (!outfile.is_open())

{

cout << "Failed to open file " << output_file_name

<< " for output\n";

return;

}

cout << "Writing file " << output_file_name << endl;

outfile << "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n";

outfile << "<USA>\n";

// Tell each state to output itself

outfile << "</USA>\n";

outfile.close();

cout << "File " << output_file_name << " written\n";

}

4

Command_Processor.cpp

Add

#include <fstream>

5

6

Comand_Processor.h

Add to private section:

static void Output_XML();

6

Saving the Changes

void Command_Processor::Process_Commands(State** states_,

int* nr_states_)

{

cout << "Process_Commands starting\n";

states = states_;

nr_states = nr_states_;

Create_Menus();

while (command_state != Done)

{

...

}

Output_XML();

cout << "Process_Commands exiting\n";

}

7

Try it!

8

Look at state2.xml

So far so good!

9

Saving the Changes

Now we need to add code to class State and class City to let objects write their data out to an XML file.

Add to state.h and city.h:

#include <fstream>...

void Output_XML(std::ofstream& outfile) const;

10

State.cppvoid State::Output_XML(ofstream& outfile) const

{

outfile << "\t<state>\n";

outfile << "\t\t<name>\n";

outfile << "\t\t\t" << name << "\n";

outfile << "\t\t</name>\n";

outfile << "\t\t<capital>\n";

outfile << "\t\t\t" << capital << "\n";

outfile << "\t\t</capital>\n";

list<City>::const_iterator c;

c = cities.begin();

while (c != cities.end())

{

if (c->Name() == capital)

{

++c;

continue;

}

c->Output_XML(outfile);

++c;

}

cout << endl;

outfile << "\t</state>\n";

} 11

12

City.cpp

#include <fstream>

void City::Output_XML(std::ofstream& outfile) const

{

outfile << "\t\t<city>\n";

outfile << "\t\t\t" << name << "\n";

outfile << "\t\t</city>\n";

}

12

13

Command_Processor::Output_XML

// Tell each state to output itself

for (int i = 0; i < *nr_states; ++i)

{

states[i]->Output_XML(outfile);

}

Build and run.

13

14

Program Running

14

15

states2.xml

<?xml version="1.0" encoding="utf-8"?>

<USA>

<state>

<name>

Florida

</name>

<capital>

Tallahassee

</capital>

<city>

Clearwater

</city>

<city>

Miami

</city>

<city>

Tampa

</city>

</state>

...

15

<state>

<name>

New York

</name>

<capital>

Albany

</capital>

<city>

Buffalo

</city>

<city>

New York City

</city>

</state>

<state>

<name>

New Mexico

</name>

<capital>

Santa Fe

</capital>

<city>

Las Vegas

</city>

</state>

</USA>16

Test the Output File

Let's check that the output file works as an input file.

Rename states.xml to states_0.xml states2.xml to states.xml

17

The New Information is There

18