Getting hashtags from a string - C# Discussion Boards

Getting hashtags from a string

2-Jul-15 21:34

Equations may look like code, but in practice they are very different.

You need to ask a physicist, not a developer.

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Farhad Eft2-Jul-15 8:26

Farhad Eft

2-Jul-15 8:26

Hi,

I have a string that may contains several hashtags starting with # like this example:
"Hello, I am #Hashtag1 and #Hashtag2"

I want to save those hashtags, as many as they are, in an array.

Can anyone help me how to do it.

Thank you in advance.

OriginalGriff2-Jul-15 8:46

2-Jul-15 8:46

Use a regex to identify them:

\#\w*

You can then use the Regex.Matches to convert them to a collection with Linq methods:

string[] hashtags = Regex.Matches(myDate, @"\#\w*").Cast<Match>().Select(m => m.Value).ToArray();

[edit]Matches, not Match, Griff Sigh | :sigh:

[/edit]

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

modified 2-Jul-15 15:20pm.

Richard Deeming2-Jul-15 9:13

Richard Deeming

2-Jul-15 9:13

That should be Regex.Matches, not Regex.Match.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

OriginalGriff2-Jul-15 9:21

2-Jul-15 9:21

Clearly, I read what I meant to type... D'Oh! | :doh:

Thanks!

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Farhad Eft2-Jul-15 10:02

Farhad Eft

2-Jul-15 10:02

thank you so much, it worked perfectly Smile | :)

OriginalGriff2-Jul-15 10:17

C# How about coordinates and matrix

2-Jul-15 10:17

You're welcome!

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Siao Da2-Jul-15 2:51

Siao Da

2-Jul-15 2:51

I have written a 3 by 3 matrix program where I assume that the matrix represents the circle. It is able to tell the coordinates of the axes as well as the origin.
For example a 3 by 3 matrix, it will display these results which are what I want. The program will find the origin automatically by taking the 3 minus by 1 then divide by 2.
Index=[0,0](x,y)=(-38,38)
Index=[0,1](x,y)=(0,38)
Index=[0,2](x,y)=(38,38)

Index=[1,0](x,y)=(-38,0)
Index=[1,1](x,y)=(0,0)
Index=[1,2](x,y)=(38,0)

Index=[2,0](x,y)=(-38,-38)
Index=[2,1](x,y)=(0,-38)
Index=[2,2](x,y)=(-38,-38)

However, when I want to do a 4 by 4 matrix and so on, the result of the coordinates does not match with my calculation. Is there any formula for this?
1 unit=38
4 by 4 matrix would be

Index=[0,0] (x,y)=(-76,76)
Index=[0,1] (x,y)=(-38,76))
Index=[0,2] (x,y)=(0,76)
Index=[0,3](x,y)=(38,76)

Index=[1,0] (x,y)=(-76,38)
Index=[1,1] (x,y)=(-38,38)
Index=[1,2] (x,y)=(0,38)
Index=[1,3] (x,y)=(38,38)

Index=[2,0] (x,y)=(-76,0)
Index=[2,1] (x,y)=(-38,0)
Index=[2,2] (x,y)=(0,0)
Index=[2,3] (x,y)=(38,0)

Index=[3,0] (x,y)=(-76,-38)
Index=[3,1] (x,y)=(-38,-38)
Index=[3,2] (x,y)=(0,-38)
Index=[3,3] (x,y)=(38,38)

Tomorrow, I will post my code because my file is broken and I can only retrieve from my workplace. Please help me.

Re: C# How about coordinates and matrix

Traitorous2-Jul-15 22:45

Traitorous

2-Jul-15 22:45

Explain your problem properly.

"I have written a 3 by 3 matrix program where I assume that the matrix represents the circle"

What circle? How does a Matrix represent a circle?

"It is able to tell the coordinates of the axes as well as the origin."
Who is able to tell the coordinate of what?

"The program will find the origin automatically by taking the 3 minus by 1 then divide by 2."
3 what? 1 what?

Re: C# How about coordinates and matrix

Eddy Vluggen3-Jul-15 3:11

Eddy Vluggen

3-Jul-15 3:11

https://www.mathsisfun.com/algebra/circle-equations.html[^] $Shucks | :-\$

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

overriding equals

Gilbert Consellado1-Jul-15 18:52

Gilbert Consellado

1-Jul-15 18:52

public class User{
  public int UserID {get;set;}
  public string Username {get;set;}

publict override bool Equals(object obj)
{
  if(!(obj is User)) return false;
  return (obj as User).UserID == UserID;
}

public override int GetHashCode()
{
  //UserID is form the database
  return UserID;
}

public override ToString()
{
  return Username;
}
}

base on the code above, when i create to object from the database, comparing them will return false even they are the same.

example:

User u1 = new User(){UserID = 1, Username = "FirstUser"};
User u2 = new User(){UserID = 1, Username = "FirstUser"};

var b = u1 == u2;

variable b is false;
I thought they will be the same,
is there i missing there?

I will appreciate for any advice will be given

Thank you.

Brisingr Aerowing1-Jul-15 19:23

Brisingr Aerowing

1-Jul-15 19:23

You need to override the == and != operators.

public static bool operator ==(User lhs, User rhs)
{
    if(lhs == null && rhs == null) return true;
    if(lhs == null && rhs != null) return false;
    if(lhs != null && rhs == null) return false;
    return lhs.UserID == rhs.UserID;
}

public static bool operator !=(User lhs, User rhs)
{
    return !(lhs == rhs);
}

Just insert these into the class and you will be able to use == and != to check for equality and inequality.

Note that if you override one, C# forces you to override the other.

There are several other operators you can override. You can get all the nitty gritty details on MSDN[^].

What do you get when you cross a joke with a rhetorical question?

The metaphorical solid rear-end expulsions have impacted the metaphorical motorized bladed rotating air movement mechanism.

Do questions with multiple question marks annoy you???

Gilbert Consellado1-Jul-15 19:41

Gilbert Consellado

1-Jul-15 19:41

thank you for the quick reply.

I thought overriding equals will be enough,

By the way, one more question base on the code above, which is most efficient using the "Equals" method or the equals operator?

Thank you

http://blogs.msdn.com/b/csharpfaq/archive/2004/03/29/when-should-i-use-and-when-should-i-use-equals.aspx[^]

F-ES Sitecore2-Jul-15 0:20

F-ES Sitecore

2-Jul-15 0:20

Richard Deeming2-Jul-15 2:06

Richard Deeming

2-Jul-15 2:06

As you're dealing with a class, not a struct, you can simplify the operator to:

public static bool operator ==(User lhs, User rhs)
{
    return Equals(lhs, rhs);
}

public static bool operator !=(User lhs, User rhs)
{
    return !Equals(lhs, rhs);
}

The static Equals method[^] will perform the null checks for you, and then call the instance Equals method on the first parameter:

public static bool Equals(Object objA, Object objB) 
{
    if (objA==objB) {
        return true;
    }
    if (objA==null || objB==null) {
        return false;
    }
    return objA.Equals(objB);
}

At first glance, it might look like the first line of that method would cause a stack overflow, since your == operator is calling a method that calls the == operator. However, within the Equals method, it's calling the == operator on the Object type, which just tests for reference equality.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Gilbert Consellado2-Jul-15 3:27

Gilbert Consellado

2-Jul-15 3:27

Thank you, for all the hint, i finally got it now