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Hello.

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In this lecture, we're going to talk about Topic 48.

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What is the difference between debug and release builds when using Visual Studio?

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It's hard not to notice this little option in the top menu.

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When developing the code, we most likely use Ladybug mode, and we don't really think much about the

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other option.

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The release mode as their name suggests, the debug mode is most appropriate when debugging the application,

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so mostly during the development and the release mode can be used when we intend to release the application

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so it can be used by users or other programs.

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But what is the difference between them exactly?

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The main difference is that in the released build, the compiler introduces some optimizations it finds

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appropriate.

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They can be things like removing unused variables or simplifying method calls.

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It helps to make the final common intermediate language code smaller, simpler and often faster.

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Remember that the common intermediate language is the language to which the compiler compiles this code.

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Those optimizations shouldn't be done in the debugging mode because they can make debugging harder as

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the compound result doesn't match exactly the source code.

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Let's see the simple compiler optimizations in practice.

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First, let's see some code that is not optimal.

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This variable is not used.

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First, I will build this project in the debug mode.

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The result of compilation should end up in the Dimmock folder.

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The fastest way to go down is by right clicking on the product and selecting Open Folder in File Explorer.

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Let's find the compound Diallo.

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It is in the Dybbuk folder, a six pack that would I'm going to do now is to first use IL dozen to see

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the common intermediate language code.

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Then we will translate this code back to C-sharp to see how the compilation affected the structure of

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the code.

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You can find it does an application under such path.

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Let's run it.

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Now we can simply drag that yellow and drop it to your Dawson.

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To save the common intermediate language called in the file, we must select, file and dump.

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And here it is.

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Let's open it with Notepad.

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Here is the common intermediate language code that's now copied and pasted on this web page.

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Chopped up allows us to compile the common intermediate language code to see towards C-sharp code,

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it translates to.

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And here it is.

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Let's fund the program class.

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And this is how it looked like originally.

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Well, the changes done by the compiler are not very exciting.

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We can see that the unused variable has been renamed to something shorter and that the strings have

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been learned.

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Now let's do the same thing.

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But in the release build.

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First of all, the result of compensation should end up in the release folder.

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Here it is.

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I will again drop the deal to elders and save the common intermediate language code and then paste it

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to our club.

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This time, the Houston variable has been removed completely.

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This is just an extremely simple example of what the compiler can optimize in the release mode.

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But be aware that those optimizations can be much more serious.

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The compiler can simplify or in-line.

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The method calls remove whole pieces of code that it doesn't find useful, etc. the algorithm behind

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it that is quite sophisticated and it depends on the compiler version as well.

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As such, low level details like how big the methods are, we can configure some of the optimization

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settings.

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For example, if we don't want some method to be in line, we can add the no inclining attribute to

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it.

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In the article attached to this lecture, I left a link to an article in which you can read more about

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that.

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The code optimization done by the compiler is the main difference between the debug and release modes.

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Please note that if we want some code to be executed only in one of those modes, we can put it in if

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debug or if release conditions are pre-processed or directives.

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Now this line will be executed if you run the application built in the realist mode.

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If you are in the debug mode.

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This line will be run.

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And here it is, makes sense because the realist mold was selected here.

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Let's summarize during the release build, the compiler applies optimizations it finds appropriate.

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Because of that, the result of the build is often smaller and it works faster.

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On the other hand, it's harder to debug because the compiled result doesn't match the source code exactly.

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During the interview.

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You can be asked How can we execute some piece of code only in the debug or only in the release mode

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by simply placing this code inside?

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If the bug or if this conditional preprocessor directives will actually talk more about them in the

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next lecture.

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Thanks for watching this one, and I'll see you there.