Selecting a substring from a string in C#

Question

I am looking to find a string with in a string.

Lets say I have 2 strings:

String1 = "1.1)The Element is"

String2 = "1.1)The Element is:(-) for the sub"

If I compare String1 with String2, I can get "1.1)The Element is" which is ok.

 int Length_Str1 = string1.Length;

 string2 = string2.Remove(Length_Str1);

But I also want to get the non-alphabetical characters ":(-)". I am thinking to keep extracting the character until a space character is found. But I don't know how I can do it in C#.

@Tijesunimi yes. But this is only 1 Example I have more strings. — Kamran
– Kamran, Commented Mar 4, 2014 at 13:47

Tim Schmelter · Accepted Answer · 2014-03-04 14:29:24Z

2

You could take chars so long as Char.IsLetter and Char.IsWhiteSpace return false:

int index = String2.IndexOf(String1);
if(index >= 0)
{
    string result = String1;
    if (String1.Length < String2.Length)
    {
        string rest = String2.Substring(index + String1.Length);
        var chars = rest.TakeWhile(c => !Char.IsLetter(c) && !Char.IsWhiteSpace(c));
        result = result + string.Join("", chars);
    }
}

Note that you have to add using System.Linq; at the top of the file.

edited Mar 4, 2014 at 14:29

answered Mar 4, 2014 at 13:53

Tim Schmelter

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3 Comments

Kamran Over a year ago

I am having an error on this line, var takeChars = rest.Where(c => !Char.IsLetter(c) && !Char.IsWhiteSpace(c)); The Error is: Cannot convert lambda expression to type 'System.Func<char,int,bool>' because it is not a delegate type

Tim Schmelter Over a year ago

@Kami: i have tested it with your sample strings. What framework version are you using, have you added using System.Linq;?

Kamran Over a year ago

Yes I added the library. But let me check again.

Hash Sling Slasher · Accepted Answer · 2014-03-04 13:59:41Z

1

var String1 = "1.1)The Element is";
var String2 = "1.1)The Element is:(-) for the sub";
var result = string.Empty;
if(String2.Contains(String1))
{
    result = String1 + Regex.Match(String2.Replace(String1, string.Empty), "[^\\sa-zA-Z0-9]+").ToString();
}

//result will contain String1 + ":(-)" from String2 IF there is a match

answered Mar 4, 2014 at 13:59

Hash Sling Slasher

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1 Comment

RvdV79 Over a year ago

+1 for having the same idea as mine, at least your answer is quicker lol. I spent way too much time to explain everything... :(

Sadique · Accepted Answer · 2014-03-04 14:01:03Z

1

How about this:

string s = "1.1)The Element is:(-) for the sub";
s = s.Substring(0, s.IndexOf("(-) ") + "(-) ".Length);

This gives 1.1)The Element is:(-)

string s = "1.1)The Element is:(-) for the sub";
s = s.Substring(s.IndexOf("(-) ") + "(-) ".Length);

This gives for the sub. Going by your comment:

 string String1 = "1.1)The Element is";

 string String2 = "1.1)The Element is:(-) for the sub";
 if(String2.Contains(String1))
 {
      string s = String2.Substring(String2.IndexOf(String1)+ String1.Length);
      s = s.Substring(s.IndexOf(" ")+1);  // +1 to leave space
 }

edited Mar 4, 2014 at 14:01

answered Mar 4, 2014 at 13:47

Sadique

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6 Comments

Kamran Over a year ago

Its not always the case, some strings contains "(-)". Some contains ")" Some contains ":" and some contains "-". I need some how to keep getting the characters until a space is found.

Sadique Over a year ago

Your logic is flawed - the space is even after the, element, etc - how do you plan to differentiate them?

Kamran Over a year ago

it should starting finding the space once the matching is found.

Sadique Over a year ago

Matching for what is found?

Kamran Over a year ago

match string1 with string2, matching is found now find the first space after the matching string.

|

RvdV79 · Accepted Answer · 2014-03-04 14:32:16Z

This could be solved with a regular expression quite easily:

//Note the special escape character here for the regex engine not to fail on a found ')'
string string1 = @"1.1\)The Element is:";

List<string> testStrings = new List<string>();
testStrings.Add(@"1.1)The Element is:(-) for the sub 1");
testStrings.Add(@"1.1)The Element is:) for the sub 2");
testStrings.Add(@"1.1)The Element is:[-] for the sub 3");

//Create a regular expression string based upon the 'string1' provided above.
string regularExpression = string.Format(@"(?<base>{0})+(?:[^\\sa-zA-Z0-9]+)", string1);
Regex regex = new Regex(regularExpression, RegexOptions.Multiline);
//Will contain the found results
List<string> subStrings = new List<string>();

foreach (string str in testStrings)
{
  foreach (Match match in regex.Matches(str))
  {
    if (match.Success)
    {
      subStrings.Add(str.Replace(match.Groups[0].ToString(), string.Empty));
    }
  }
}
//Display the found results
foreach (string str in subStrings)
{
  Console.WriteLine(str);
}

After executing this code, it will yield the following results:

for the sub 1 
for the sub 2 
for the sub 3

I am not sure if this is what you are looking for, but this code makes it able to have different patterns after 'is:'.

Edit: Hash Sling Slasher just provided the same answer, albeit a bit smaller :)

Selman Genç · Accepted Answer · 2014-03-04 13:49:31Z

0

How about using Split and string.Join like this ?

var str1 = "1.1)The Element is";
var str2 = "1.1)The Element is:(-) for the sub";

str2 = string.Join(" ",str2.Split().Take(str1.Count(x => x == ' ')+1));

answered Mar 4, 2014 at 13:49

Selman Genç

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Comments

Tor-Erik · Accepted Answer · 2014-03-04 13:53:53Z

0

The following code should find the index of the first space after the length of string1.

int Length_Str1 = string1.Length;

string2 = string2.Remove(string2.IndexOf(' ', Length_Str1));

Please note that you should also add some checks to make sure that string2 is longer than string1 and that .IndexOf actually finds a space.

answered Mar 4, 2014 at 13:53

Tor-Erik

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Comments

Oscar Bralo · Accepted Answer · 2014-03-04 13:55:09Z

0

You can do something like:

At least if your string is always with the same format ;)

string result = string.Join(" ", string1.Split(' ').Take(3).ToArray<string>());

I hope this helps

edited Mar 4, 2014 at 13:55

answered Mar 4, 2014 at 13:49

Oscar Bralo

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