Byline Xml Made Easy

Byline xml

hi this is Ben Bryant of first object comm here is an XML file called Plato XML I'll open it up in the first object XML editor to see the structure better let's format it with an indent you could press f8 you can see the title element is the immediate child of the root play element I'd like to create an app that extracts the play title and displays it in a message box using C markup the C++ XML parser I'll create an app in Visual C++ 2008 Express a new project I'm going to resize this dialogue to fit inside of the video window it's a win32 project give it the name XML example it's going to create the files for this project inside of the C colon slash XML example folder which happens to be where I had already put the played XML file that I just showed you here's the project I have to add C markup to it so I'm going to go to the web and download C markup current version is 10.1 the zip file comes with a test project and the main of the two files that I need are mark up dot CPP and markup H I'm going to copy these over to the application folder XML example paste them in there now they're in the folder but I also have to add them into the project right click on the project name there in the solution Explorer add existing item I can select in this dialog both the markup dot CPP and markup h files and click Add to move it up here now the files are in the solution Explorer as part of the project there are markup CP I'm going to click on the properties you can't see it in the window but it's on the right-click menu because I'm in visual C++ which defaults to use precompiled headers I have to turn it off for markup dot CPP specifically the other change I need to make is in the project properties so I'll go back into here and instead of clicking on markup dot CPP click on XML example and choose properties again from the right-click menu go into C C++ preprocessor definitions and I want to use STL strings instead of um M FC C string which it defaults to see markup defaults to use M FC C strings when you're in Visual Studio but only in Visual Studio so in Visual Studio if you want to use STL strings you have to explicitly specify them there here I've included markup eh and go down and I'm going to instantiate a C markup object call it the XML and now I need to load the XML file called played on XML it happens to be in the current folder otherwise I would specify a full path the m CD underscore T macro is used to make it a wide string because my default project settings or wide strings in Visual C++ 2008 once after I've loaded the document I go to the root element play element I don't need to specify the tag name because it's the first one go inside of it and then find the title element in this case I'm going to specify the title tag node ah even though I know that the title happens to be the first element inside of the play element but so in this case it's optional finally I'm going to extract the title into a string variable see here are explicitly instantiated a w string variable and now I'm going to display the title in a message box to turn a standard string into a constant string pointer wide string pointer you can use the c markup compiler defend dependent define to PCSD or you can just use the standard string method c underscore str to ways of getting a constant string pointer constant wide string pointer now we'll give the message box a title just call it XML and give it a okay button that's all now we can compile it f7 and run it control f5 to run without debugging there we've shown a message box with the information we extracted now to get a better idea of what's going on let's set a breakpoint and actually debug into this and step through what is going on with the c markup object I'm going to start debugging f5 and C before I've actually loaded the play XML file I can look at my XML object and see that there is an empty document strength now I'm going to step and actually perform the load you can see now that my document string contains the document that was loaded the mark is very simple like that it just has one string containing the document the text of the document that was loaded now look at the main des member is a debugging member that shows the current position which is empty until I find the play element the root play element okay I just stepped now it points to the play element it points to that offset within the document string to show you during debugging where you are now I'm going to go into the play element now there is no current position I'm actually before the title element in the document now I'm going to find the title op element and the main position now points to the title element now I'm going to extract the data from that title element and that puts the the information into the title string thank you very much for your time