Find first non-repeated character in a string

[Alex]

How in C#?

[Justin Rogers]

Please clarify what you mean by non-repeated with a couple of string
examples.

You should be able to use regular expressions along with some
look-ahead/look-behind assertions to find what you are looking for.
--
Justin Rogers
DigiTec Web Consultants, LLC.

"Alex" <a.*******@veri zon.net> wrote in message
news:uc******** ******@TK2MSFTN GP10.phx.gbl...

How in C#?

[smart_yuppy]

Hello,
I have done this using C#.NET and collection classes.

private void button1_Click(o bject sender, System.EventArg s e)
{
String str = textBox1.Text.T rim();
function(str);
}

private void function(String str)
{
int a=str.Length;
Hashtable h = new Hashtable();

for(int i=0;i<a;i++)
{
String c = str.Substring(i ,1);
if(h.Contains(c ))
{
int f=GetValue(ref h,c);
h.Remove(c);
h.Add(c,f + 1);
}
else
{
h.Add(c,1);
}
}

for(int i=0;i<a;i++)
{
String g = str.Substring(i ,1);
if(GetValue(ref h,g)==1)
{
textBox2.Text=g ;
break;
}
}
}

private int GetValue(ref Hashtable h, String s)
{
IDictionaryEnum erator de = h.GetEnumerator ();
int d = 0;
while(de.MoveNe xt())
{
if(de.Key.ToStr ing() ==s)
{
d=Convert.ToInt 32(de.Value.ToS tring());
break;
}
}
return d;
--
smart_yupp
-----------------------------------------------------------------------
smart_yuppy's Profile: http://www.msusenet.com/member.php?userid=171
View this thread: http://www.msusenet.com/t-18363

[Jon Skeet [C# MVP]]

smart_yuppy <sm************ ****@no-mx.msusenet.com > wrote:

I have done this using C#.NET and collection classes.

Note that there is no reason to pass your hashtable reference *by*
reference - and that a somewhat easier to understand version of
str.Substring(i , 1) is str[i] (as a char, rather than a string -
there's no need to create new strings all over the place). Simpler
still though, you can just use a foreach over the string to get each
character in turn.

You're also completely ignoring the whole point of a hashtable - that
you don't have to step through each element of it. You also don't need
to convert the value in the hashtable to a string and back, and you
don't need to remove the previous value if you use the indexer rather
than the Add method. At that point it's not really worth having a
separate method in the first place.

Here's a briefer version of your code:

private void function(String str)
{
Hashtable h = new Hashtable();

foreach (char c in str)
{
if (h.ContainsKey( c))
{
h[c] = ((int)h[c])+1;
}
else
{
h[c] = 1;
}
}

for (int i=0; i < str.Length; i++)
{
char c = str[i];
if (h[c].Equals(1))
{
textBox2.Text = c.ToString();
break;
}
}
}

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too