从C＃中的字符串中选择子字符串

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#.

Answer 1

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.

Answer 2

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
 }

Answer 3

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

Answer 4

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 :)

Answer 5

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));

Answer 6

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

Answer 7

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.