Open a random file with C#?

OrangeNRG · Oct 12, 2013

I'm trying to learn how to use C# to open a random file within a folder on my hard drive. The purpose of this is to run the code midway through a macro to automate a process. The files will usually be videos but could be any type. I've searched but if anybody could point me to the right direction, please do.

Code:

http://stackoverflow.c0m/questions/742887/select-random-file-from-directory

This is the best I've found but that looks like he's doing it on a website and not his computer

rootjazz · Oct 12, 2013

From the top of my head I would do

Code:

1) get an array of files in a folder, hint use DirectoryInfo.GetFiles(..) GetFiles will take a file type filter I believe
2) Select an index at random, hint use Random

If you get stuck with the code, post up your questions.

d4dennis · Oct 12, 2013

Hi There,

The example showing on the website is exactly what you need.

What do you mean "he is doing it on a website not his computer" ?

Example:

Code:

[FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2]            
[/SIZE][/FONT][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#008000][FONT=Consolas][SIZE=2][COLOR=#008000][FONT=Consolas][SIZE=2][COLOR=#008000]// get an array of all files. [SIZE=2][FONT=Consolas]Server.MapPath([FONT=Consolas][COLOR=#a31515][FONT=Consolas][COLOR=#a31515][FONT=Consolas][COLOR=#a31515]"~/app_data/video/"[/COLOR][/FONT][/COLOR][/FONT][/COLOR][/FONT][FONT=Consolas][FONT=Consolas])[/FONT][/FONT][/FONT][/SIZE] convert relative path to computer path e.g. c:\inetpub\wwwroot\app_data\video\[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT]
[FONT=Consolas][SIZE=2][COLOR=#008000][FONT=Consolas][SIZE=2][COLOR=#008000][FONT=Consolas][SIZE=2][COLOR=#008000]
[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2]            
[/SIZE][/FONT][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff]string[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2][] allfiles = System.IO.[/SIZE][/FONT][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#2b91af][FONT=Consolas][SIZE=2][COLOR=#2b91af][FONT=Consolas][SIZE=2][COLOR=#2b91af]Directory[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2].GetFiles(Server.MapPath([/SIZE][/FONT][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#a31515][FONT=Consolas][SIZE=2][COLOR=#a31515][FONT=Consolas][SIZE=2][COLOR=#a31515]"~/app_data/video/"[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2]));[/SIZE][/FONT][/SIZE][/FONT]
[FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2]
            
[/SIZE][/FONT][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#008000][FONT=Consolas][SIZE=2][COLOR=#008000][FONT=Consolas][SIZE=2][COLOR=#008000]// use random index to retrieve file[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT]
[FONT=Consolas][SIZE=2][COLOR=#008000][FONT=Consolas][SIZE=2][COLOR=#008000][FONT=Consolas][SIZE=2][COLOR=#008000]
[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2]            
[/SIZE][/FONT][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff]string[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2] filename = allfiles[[/SIZE][/FONT][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff]new[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#2b91af][FONT=Consolas][SIZE=2][COLOR=#2b91af][FONT=Consolas][SIZE=2][COLOR=#2b91af]Random[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2]().Next(0, allfiles.Length-1)];[/SIZE][/FONT][/SIZE][/FONT]

Feel free to show what you have if youstill having problem.

Good luck!

sm754 · Oct 12, 2013

d4dennis said:

Code:

[FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff]string[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2] filename = allfiles[[/SIZE][/FONT][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff][FONT=Consolas][SIZE=2][COLOR=#0000ff]new[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][COLOR=#2b91af][FONT=Consolas][SIZE=2][COLOR=#2b91af][FONT=Consolas][SIZE=2][COLOR=#2b91af]Random[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Consolas][SIZE=2][FONT=Consolas][SIZE=2]().Next(0, allfiles.Length-1)];[/SIZE][/FONT][/SIZE][/FONT]

This part needs to be changed; if you make a new Random every time you call the function, you may end up with the same value multiple times, since it's seeded from the system clock. I usually just keep a static, global Random object with threadlocks. Other than that, the code looks fine.
edit: if it's in a macro, you can probably disregard this. This is a problem for functions which can be called multiple times in one second

OrangeNRG · Oct 12, 2013

Thank you guys. I'm still stuck on a couple errors. I looked them up and no luck. I will hand write a 500 word article for the person who can help me to get this to work properly.

qrazy · Oct 12, 2013

You can just ignore Server.Mappath and pass in the directory as a string like GetFiles("c:\\something\\")

And for the second error leave a space between 'new' and 'Random'

OrangeNRG said:
Thank you guys. I'm still stuck on a couple errors. I looked them up and no luck. I will hand write a 500 word article for the person who can help me to get this to work properly.

Jannes · Oct 12, 2013

Maybe you need to read and try to understand what you are doing.
http://msdn.microsoft.com/en-us/library/67ef8sbd.aspx

OrangeNRG · Oct 12, 2013

qrazy said:
You can just ignore Server.Mappath and pass in the directory as a string like GetFiles("c:\\something\\")

And for the second error leave a space between 'new' and 'Random'

Thanks for the help.

PM me for an article

Chris22 · Oct 29, 2013

You could use Linq

Code:

string file = Directory.GetFiles(Directory.GetCurrentDirectory()).OrderBy(x => Guid.NewGuid()).First()

always eval · Nov 29, 2013

I second the need the for a global static random. Without it, if a function is called fast enough it can produce the same results.

Also when using Random.Next() and Array.Length there is no need to put -1. You are giving the inclusive lower and exclusive upper numbers. (Random.Next() will never hit the top number)

If you have 10 objects in your array there indexes are 0-9 meaning Array.Length = 10 which is fine. When you minus one the last object in your array is never being used.

(I tried posting the Random.Next() msdn reference,but I can't post links yet)

neutralhatter · Dec 2, 2013

what are you talking about, op doesn't need a global static random. and if you do, you can just create a static class for it.

(though anyone creating a web app should never do this, this can only be stable in client side applications)

always eval said:
I second the need the for a global static random. Without it, if a function is called fast enough it can produce the same results.

Also when using Random.Next() and Array.Length there is no need to put -1. You are giving the inclusive lower and exclusive upper numbers. (Random.Next() will never hit the top number)

If you have 10 objects in your array there indexes are 0-9 meaning Array.Length = 10 which is fine. When you minus one the last object in your array is never being used.

(I tried posting the Random.Next() msdn reference,but I can't post links yet)

always eval · Dec 4, 2013

neutralhatter said:
what are you talking about, op doesn't need a global static random. and if you do, you can just create a static class for it.

(though anyone creating a web app should never do this, this can only be stable in client side applications)

In this particular case you are correct, it is not required.

Was sort of just agreeing with some insight shared above that creating a new Random object each time a function is called can be problematic if the function is called fast enough.

seeplusplus · Dec 4, 2013

Has this been solved yet? Like the first post, form an array any select any element by random().

Index != type and all that.

anaman123456 · Jan 4, 2014

private string getrandomfile(string path)
{
ArrayList al = new ArrayList();
DirectoryInfo di = new DirectoryInfo(path);
FileInfo[] rgFiles = di.GetFiles("*.*");
foreach (FileInfo fi in rgFiles)
{
al.Add(fi.FullName);
}

Random r = new Random();
int x = r.Next(0,al.Count);

return al[x].ToString();

}

Open a random file with C#?

OrangeNRG

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rootjazz

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d4dennis

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sm754

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Jannes

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OrangeNRG

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Chris22

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always eval

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neutralhatter

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always eval

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