The `byte` keyword is an alias for the `System.Byte` data type.

They represent the same data type, so the resulting code is identical. There are only some differences in usage:

- You can use `byte` even if the `System` namespace is not included. To use `Byte` you have to have a `using System;` at the top of the page, or specify the full namespace `System.Byte`.

- There are a few situations where C# only allows you to use the keyword, not the framework type, for example:

.

    enum Fruits : byte // this works
    {
      Apple, Orange
    }

    enum Fruits : Byte // this doesn&#39;t work
    {
      Apple, Orange
    }

For detailed other alias, please follow the [link][1].


  [1]: https://stackoverflow.com/a/215422/7171758

`byte` and `System.Byte` in C# are identical. `byte` is simply syntactic sugar, and is recommended by StyleCop (for style guidelines).

No difference. `byte` is alias to System.Byte, the same way `int` is alias to System.Int32, `long` to System.Int64, `string` to System.String, ...

C# has a number of aliases for the .NET types. `byte` is an alias for `Byte` just as `string` is an alias for `String` and `int` is an alias for `Int32`. I.e. `byte` and `Byte` are the same actual type. 

Nothing, the lowercase one is a keyword which is an alias for the Byte type.

This is pure syntactic sugar.

`byte` is a built-in data type in C#.  
`System.Byte` is a struct that represent a `byte` and provides extra methods like `Parse` and `TryParse`.

`byte` is alias of `System.Byte` struct. Different .NET languages have different aliases based on the semantics of the particular language, but they all map to specific types in the .NET framework.
 

also when using reflection ,,,

    Type t=Type.GetType(&quot;System.Byte&quot;); //works
    
    Type t=Type.GetType(&quot;System.byte&quot;); //doesn&#39;t work, I can see no way to use&quot;byte&quot; directly here without converting it to &quot;Byte&quot;


##Original Question

I was invited to the kindergarten group of my elder daughter to talk and answer the kids&#39; questions about my profession. There are 26 kids of age 4-6 in the group, plus 3 teachers who are fairly scared of anything related to programming and IT themselves, but bold enough to learn new tricks. I would have about 20-30 minutes, without projector or anything. They have an old computer though, which by its look may be a 486, and I am not even sure if it&#39;s functioning (Update: it isn&#39;t).

My research turned up excellent earlier threads, with lots of good tips:

- [How would you explain your job to a 5-year old?](https://stackoverflow.com/questions/526357/how-would-you-explain-your-job-to-a-5-year-old)
- [Career Day: how do I make “computer programmer” sound cool to 8 year olds?](https://stackoverflow.com/questions/207278/career-day-how-do-i-make-computer-programmer-sound-cool-to-8-year-olds)
- [What things can I teach a group of children about programming in one day?](https://stackoverflow.com/questions/2427799/what-things-can-i-teach-a-group-of-children-about-programming-in-one-day)

My situation is different from each of the above though: the latter ones are concerned with older children, while the first one is about talking to a single kid (or elder person) &amp;mdash; a group of 20 is a _whole_ different challenge.

**How can I teach the kids and their teachers about programming in a fun way?**

---
##Plan Based on Answers

Thanks for all the amazing answers, guys :-) I don&#39;t think it makes sense to accept a single answer, but I like Jim&#39;s the most, just as the majority of SOers apparently do. However, a lot of other answers contain useful hints and ideas (some of which I will surely use on future Career days in the school...).

I put together a rough plan:

1. Briefly explain what programming is, like [in this answer][1].
2. Tell that computers are everywhere, and collect examples with the kids (as suggested in several answers below).
3. Do [Jim&#39;s presentation with the sandwiches][2].
4. If time allows, build it further:
  - explain that the strength of computers is that they remember _exactly_ what they are once taught (and demonstrate it by preparing a second sandwich, repeating all the faults of the first attempt)
  - have a second round trying to fix the bugs in the process
  - explain the concept of loops: you can make the computer prepare `n` sandwiches with a single instruction

This is my plan - I am pretty sure it will turn out very differently, so I will improvise according to the situation. The presentation is scheduled in about 2 weeks time - I will update the post afterwards and tell how it actually went...

---
##Results

Finally the day of the presentation arrived today... in brief, all went fine and it was a huge success :-)

The group turned out to be quite restless and energetic this time, so the conversation occasionally went a bit chaotic. I had to cut it short and get to the Big Sandwich Maker Show. Just as Jim described, the kids _loved_ it.

There was one unforeseen side effect though: after the first slice of bread finally got ready, _everyone_ wanted to eat! So for a while - during which I tried to keep up the conversation and explain more about programming - we had to install a sort of emergency service line with the kindergarten teachers to produce immense amounts of marmalade bread and feed the hungry crowd (this was half an hour after breakfast, for the record :-). Then we ran out of bread, which clearly meant the end of the presentation. The biggest burst of laugh erupted when after cleaning up the mess, the kids noticed that the poor computer stepped on a patch of marmalade which ruined his sock :-)

The teachers themselves were also very positively impressed - judging from the feedback, this was the best and funniest Career day in this group so far. Thanks again to all of you for the great ideas!

Things that could be improved (next time):

- When I asked &quot;do you think computers are smart?&quot;, to my surprise most of them answered &quot;no&quot;. I then asked who thinks computers are smart, and why. However I neglected to ask who thinks computers are dumb, and why - thus I think I missed some potentially intriguing answers.
- Inviting the kids to come around the table got them actively involved... but maybe a bit too actively at times. Bread slices started to disappear from the table and some of the audience mimicked the computer as closely as dipping their own fingers into the butter and the marmalade :-) So it is better to keep some distance.
- To keep the hungry crowd under control, the kids should be clearly told in advance: &quot;you can eat all the bread, but only _after_ the demonstration!&quot;

But overall, I am quite happy with the outcome. And I am sure the kids got the core message: **as a programmer, if you avoid creating a mess, you can make your bread (even with marmalade :-)**

  [1]: https://stackoverflow.com/questions/526357/how-would-you-explain-your-job-to-a-5-year-old/526390#526390
  [2]: https://stackoverflow.com/questions/2455786/career-day-in-kindergarten-how-to-demonstrate-programming-in-20-minutes/2457119#2457119

Career day in kindergarten: how to demonstrate programming in 20 minutes?

I&#39;m working on a homework project and I&#39;m supposed to perform a database query which finds flights either by the city name or the airport code, but the `flights` table only contains the airport codes so if I want to search by city I have to join on the `airports` table.

The airports table has the following columns: `code, city`  
The flights table has the following columns: `airline, flt_no, fairport, tairport, depart, arrive, fare`  
The columns `fairport` and `tairport` are the **from** and **to** airport codes.  
The columns `depart` and `arrive` are dates of departure and arrival.  

I came up with a query which first joins the flights on the `fairport` column and the `airports.code` column.  In order for me to match the `tairport` I have to perform another join on the previous matches from the first join.

	SELECT airline, flt_no, fairport, tairport, depart, arrive, fare
		FROM (SELECT * FROM flights
			INNER JOIN airports
			ON flights.fairport = airports.code
			WHERE (airports.code = &#39;?&#39; OR airports.city=&#39;?&#39;)) AS matches
		INNER JOIN airports
		ON matches.tairport = airports.code
		WHERE (airports.code = &#39;?&#39; OR airports.city = &#39;?&#39;)

My query returns the proper results and it will suffice for the purpose of the homework, but I&#39;m wondering if I can `JOIN` on multiple columns? How would I construct the `WHERE` clause so it matches the departure and the destination city/code?

Below is a &quot;pseudo-query&quot; on what I want to acheive, but I can&#39;t get the syntax correctly and i don&#39;t know how to represent the `airports` table for the departures and the destinations:

    SELECT * FROM flights
    INNER JOIN airports
    ON flights.fairport = airports.code AND flights.tairport = airports.code
    WHERE (airports.code = &#39;departureCode&#39; OR airports.city= &#39;departureCity&#39;) 
        AND (airports.code = &#39;destinationCode&#39; OR airports.city = &#39;destinationCity&#39;)

Update
----
I also found [this visual representation of SQL Join statements][1] to be **very** helpful as a general guide on how to construct SQL statements!

  [1]: http://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins

How to do an INNER JOIN on multiple columns

I noticed that in C# there are both a **byte** and **Byte** data type. They both say they are of type **struct System.Byte** and represent an 8-digit unsigned integer. 

So I am curious as to what the difference if any is between the two, and why you would use one over the other.

Thanks!

Difference between byte vs Byte data types in C#

I noticed that in C# there are both a byte and Byte data type. They both say they are of type struct System.Byte and represent an 8-digit unsigned integer.
So I am curious as to what the difference if any is between the two, and why you would use one over the other.
Thanks!

How do you simulate Mouse clicks in C# winforms applications?

How do you simulate Mouse Click in C#?

I know that I can return the index of a particular character of a string with the `indexof()` function, but how can I return the character at a particular index?

How can I get a character in a string by index?

How to use data annotations to do a conditional validation on model?

For example, lets say we have the following model (Person and Senior):


    public class Person
    {
        [Required(ErrorMessage = &quot;*&quot;)]
        public string Name
    	{
    		get;
    		set;
    	}
    
    	public bool IsSenior
    	{
    		get;
    		set;
    	}
    
    	public Senior Senior
    	{
    		get;
    		set;
    	}
    }
    
    public class Senior
    {
        [Required(ErrorMessage = &quot;*&quot;)]//this should be conditional validation, based on the &quot;IsSenior&quot; value
    	public string Description
    	{
    		get;
    		set;
    	}
    }

And the following view:

    &lt;%= Html.EditorFor(m =&gt; m.Name)%&gt;
    &lt;%= Html.ValidationMessageFor(m =&gt; m.Name)%&gt;

    &lt;%= Html.CheckBoxFor(m =&gt; m.IsSenior)%&gt;
    &lt;%= Html.ValidationMessageFor(m =&gt; m.IsSenior)%&gt;

    &lt;%= Html.CheckBoxFor(m =&gt; m.Senior.Description)%&gt;
    &lt;%= Html.ValidationMessageFor(m =&gt; m.Senior.Description)%&gt;

I would like to be the &quot;Senior.Description&quot; property conditional required field based on the selection of the &quot;IsSenior&quot; propery (true -&gt; required). How to implement conditional validation in ASP.NET MVC 2 with data annotations?

ASP.NET MVC Conditional validation

What is the difference in functionality between `StreamWriter.Flush()` and `StreamWriter.Close()`?

When my data wasn&#39;t being written correctly to a file, I added both `Flush()` and `Close()` to the end of my code.  However, I realized that adding *either* `Flush()` or `Close()` allowed the data to be written correctly.

I wasn&#39;t able to pick up on exactly what each of these methods does when I read the MSDN docs; I only figured out that one or the other is necessary to ensure data is written correctly. Any further explanation would be much appreciated.

&lt;hr&gt;

Where `s` is a string to be written, here&#39;s what my code looks like currently:


    StreamWriter sw = File.CreateText(&quot;TextOutput.txt&quot;);
    sw.Write(s);
    sw.Flush();
    sw.Close();

&lt;hr&gt;

Based on feedback from the answers, I&#39;ve rewritten my code in a `using` block, which implements `IDisposable` and will automatically take care of writing the stream to the file when the object is disposed:

    using (StreamWriter sw = File.CreateText(&quot;TextOutput.txt&quot;))
    {
        sw.Write(s);
    }



What is the difference between StreamWriter.Flush() and StreamWriter.Close()?

`Directory.GetFiles()` returns all files, even those that are marked as hidden. Is there a way to get a list of files that excludes hidden files?

C# - Get a list of files excluding those that are hidden

Is converting a file to a byte array the best way to save ANY file format to disk or database var binary column?

So if someone wants to save a .gif or .doc/.docx or .pdf file, can I just convert it to a bytearray UFT8 and save it to the db as a stream of bytes?

Saving any file to in the database, just convert it to a byte array?

In a python source code I stumbled upon I&#39;ve seen a small **b** before a string like in:

    b&quot;abcdef&quot;

I know about the **`u`** prefix signifying a unicode string, and the **`r`** prefix for a raw string literal. 

What does the `b` stand for and in which kind of source code is it useful as it seems to be exactly like a plain string without any prefix?

What does a b prefix before a python string mean?

I was initially surprised that Java decides to specify that `byte` is signed, with a range from `-128..127` (inclusive). I&#39;m under the impression that most 8-bit number representations are unsigned, with a range of `0..255` instead (e.g. [IPv4 in dot-decimal notation](http://en.wikipedia.org/wiki/Dot-decimal_notation)).

So has James Gosling ever been asked to explain why he decided that `byte` is signed? Has there been notable discussions/debates about this issue in the past between authoritative programming language designers and/or critics?

James Gosling&#39;s explanation of why Java&#39;s byte is signed

How can I encode my string as ASCII byte array?

Go string to ascii byte array

I&#39;m trying to get an image from an url using a `byte` stream. But i get this error message:

&gt; This stream does not support seek operations.

This is my code:

    byte[] b;
    HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create(url);
    WebResponse myResp = myReq.GetResponse();

    Stream stream = myResp.GetResponseStream();
    int i;
    using (BinaryReader br = new BinaryReader(stream))
    {
        i = (int)(stream.Length);
        b = br.ReadBytes(i); // (500000);
    }
    myResp.Close();
    return b;

What am i doing wrong guys?

Content Type	Original Author	Original Content on Stackoverflow
Question	jaywon	View Question on Stackoverflow
Solution 1 - C#	Guffa	View Answer on Stackoverflow
Solution 2 - C#	Adam Maras	View Answer on Stackoverflow
Solution 3 - C#	Darin Dimitrov	View Answer on Stackoverflow
Solution 4 - C#	Brian Rasmussen	View Answer on Stackoverflow
Solution 5 - C#	Gerrie Schenck	View Answer on Stackoverflow
Solution 6 - C#	Aurril	View Answer on Stackoverflow
Solution 7 - C#	ata	View Answer on Stackoverflow
Solution 8 - C#	Colin	View Answer on Stackoverflow

Difference between byte vs Byte data types in C#

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

Solution 4 - C#

Solution 5 - C#

Solution 6 - C#

Solution 7 - C#

Solution 8 - C#

How to do an INNER JOIN on multiple columns

Career day in kindergarten: how to demonstrate programming in 20 minutes?

Attributions