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Split string with plus sign as a delimiter

I have an issue with a string containing the plus sign (+).
I want to split that string (or if there is some other way to solve my problem)
string ColumnPlusLevel = "+-J10+-J10+-J10+-J10+-J10";
string strpluslevel = "";
strpluslevel = ColumnPlusLevel;
string[] strpluslevel_lines = Regex.Split(strpluslevel, "+");
foreach (string line in strpluslevel_lines)
{
MessageBox.Show(line);
strpluslevel_summa = strpluslevel_summa + line;
}
MessageBox.Show(strpluslevel_summa, "summa sumarum");
The MessageBox is for my testing purpose.
Now... The ColumnPlusLevel string can have very varied entry but it is always a repeated pattern starting with the plus sign.
i.e. "+MJ+MJ+MJ" or "+PPL14.1+PPL14.1+PPL14.1" as examples.
(It comes form Another software and I cant edit the output from that software)
How can I find out what that pattern is that is being repeated?
That in this exampels is the +-J10 or +MJ or +PPL14.1
In my case above I have tested it by using only a MessageBox to show the result but I want the repeated pattering stored in a string later on.
Maybe im doing it wrong by using Split, maybe there is another solution.
Maybe I use Split in the wrong way.
Hope you understand my problem and the result I want.
Thanks for any advice.
/Tomas

How can I find out what that pattern is that is being repeated?
Maybe i didn't understand the requirement fully, but isn't it easy as:
string[] tokens = ColumnPlusLevel.Split(new[]{'+'}, StringSplitOptions.RemoveEmptyEntries);
string first = tokens[0];
bool repeatingPattern = tokens.Skip(1).All(s => s == first);
If repeatingPattern is true you know that the pattern itself is first.
Can you maybe explain how the logic works
The line which contains tokens.Skip(1) is a LINQ query, so you need to add using System.Linq at the top of your code file. Since tokens is a string[] which implements IEnumerable<string> you can use any LINQ (extension-)method. Enumerable.Skip(1) will skip the first because i have already stored that in a variable and i want to know if all others are same. Therefore i use All which returns false as soon as one item doesn't match the condition(so one string is different to the first). If all are same you know that there is a repeating pattern which is already stored in the variable first.

You should use String.Split function :
string pattern = ColumnPlusLevel.Split("+")[0];

...but it is always a repeated pattern starting with the plus sign.
Why do you even need String.Split() here if the pattern always only repeats itself?
string input = #"+MJ+MJ+MJ";
int indexOfSecondPlus = input.IndexOf('+', 1);
string pattern = input.Remove(indexOfSecondPlus, input.Length - indexOfSecondPlus);
//pattern is now "+MJ"
No need of string split, no need to use LinQ

String has a method called Split which let's you split/divide the string based on a given character/character-set:
string givenString = "+-J10+-J10+-J10+-J10+-J10"'
string SplittedString = givenString.Split("+")[0] ///Here + is the character based on which the string would be splitted and 0 is the index number
string result = SplittedString.Replace("-","") //The mothod REPLACE replaces the given string with a targeted string,i added this so that you can get the numbers only from the string

how to change a char to the previous one of it (alphabetically) in string using c#?

hello i am searching for a good approach to change a single char in a string to the previous char of it . i mean if i have this string = "abcd" i want to change the 'd' char to 'c' ? how to change the char to to the one before it (alphabetically) ?
i want to use the approach here:
int StringSize=0;
string s=" ";
s = Console.ReadLine();
StringSize = s.Length;
s.Replace(s[StringSize-1],the previous char);
i want to change the char s [StringSize-1] to the previous char of it.
I've tried to do this depending on the ASCII code of the character but i did't find a method to convert form char to ASCII.

char is already ASCII, but to do math on it, you need a number.
So:
Cast to int
Do your math (subtract 1)
Cast back to char
char newChar = (char)((int)oldChar - 1);
Or in your code:
s = s.Replace(s[StringSize-1], (char)((int)s[StringSize-1] - 1));
Caveats:
This won't work with 'a' or 'A'
Strings are immutable you can't just change a character. You can create a new string with the replaced character, but that isn't technically the same thing.

Replace return string to object, but not change values on it. The solution's:
s = s.Replace(s[StringSize-1], the previous char);

var str = "abcd";
for (int i = 0; i < str.Length; i++)
{
str = str.Replace(str[i], (char)((byte)str[i] - 1));
}

Find if string contains at least 2 characters similar to another? C#

I need a method to check if a string contains one or more similar characters to another. I dont want to find all strings containing the letter "D".
For example, if I have a string "Christopher" and want to see if "Chris" is contained in "Christopher", I want that to return. However, if I want to see if "Candy" is in the string "Christopher", I wont want it to return just because it has a "C" in common.
I have tried the .Contains() method but cant give that rules for 2 or more similar characters and I have thought about using regular expressions but that might be a bit over kill. The similar letters must be next to eachother.
Thank you :)

This looks for each 2-character-gram of s1 and looks for it in s2.
string s1 = "Chrx";
string s2 = "Christopher";
IsMatchOn2Characters(s1, s2);
static bool IsMatchOn2Characters(string a, string b)
{
string s1 = a.ToLowerInvariant();
string s2 = b.ToLowerInvariant();
for (int i = 0; i < s1.Length - 1; i++)
{
if (s2.IndexOf(s1.Substring(i,2)) >= 0)
return true; // match
}
return false; // no match
}

This looks a lot like a longest common substring problem. This can be solved easily using DP in O(m*n).
If you are not worried about performance and don't really want to implement this, you can also go with the brute force solution of searching every substring of s1 into s2.

Is there an easy way to trim the last three characters off a string

I have strings like this:
var a = "abcdefg";
var b = "xxxxxxxx";
The strings are always longer than five characters.
Now I need to trim off the last 3 characters. Is there some simple way that I can do this with C#?

In the trivial case you can just use
result = s.Substring(0, s.Length-3);
to remove the last three characters from the string.
Or as Jason suggested Remove is an alternative:
result = s.Remove(s.Length-3)
Unfortunately for unicode strings there can be a few problems:
A unicode codepoint can consist of multiple chars since the encoding of string is UTF-16 (See Surrogate pairs). This happens only for characters outside the basic plane, i.e. which have a code-point >2^16. This is relevant if you want to support Chinese.
A glyph (graphical symbol) can consist of multiple codepoints. For example ä can be written as a followed by a combining ¨.
Behavior with right-to-left writing might not be what you want either

You want String.Remove(Int32)
Deletes all the characters from this string beginning at a specified
position and continuing through the last position.
If you want to perform validation, along the lines of druttka's answer, I would suggest creating an extension method
public static class MyStringExtensions
{
public static string SafeRemove(this string s, int numCharactersToRemove)
{
if (numCharactersToRemove > s.Length)
{
throw new ArgumentException("numCharactersToRemove");
}
// other validation here
return s.Remove(s.Length - numCharactersToRemove);
}
}
var s = "123456";
var r = s.SafeRemove(3); //r = "123"
var t = s.SafeRemove(7); //throws ArgumentException

string a = "abcdefg";
a = a.Remove(a.Length - 3);

string newString = oldString.Substring(0, oldString.Length - 4);

If you really only need to trim off the last 3 characters, you can do this
string a = "abcdefg";
if (a.Length > 3)
{
a = a.Substring(0, a.Length-3);
}
else
{
a = String.Empty;
}

Copy first few strings separated by a symbol in c#

I have a string consist of integer numbers followed by "|" followed by some binary data.
Example.
321654|<some binary data here>
How do i get the numbers in front of the string in the lowest resource usage possible?
i did get the index of the symbol,
string s = "321654654|llasdkjjkwerklsdmv"
int d = s.IndexOf("|");
string n = s.Substring(d + 1).Trim();//did try other trim but unsuccessful
What to do next? Tried copyto but copyto only support char[].

Assuming you only want the numbers before the pipe, you can do:
string n = s.Substring(0, d);
(Make it d + 1 if you want the pipe character to also be included.)
I might be wrong, but I think you are under the impression that the parameter to string.Substring(int) represents "length." It does not; it represents the "start-index" of the desired substring, taken up to the end of the string.

s.Substring(0,d);

You can use String.Split() here is a reference http://msdn.microsoft.com/en-us/library/ms228388%28VS.80%29.aspx
string n = (s.Split("|"))[0] //this gets you the numbers
string o = (s.Split("|"))[1] //this gets you the letters