Develop Reference

Shortcut for splitting only once in C#?

Okay, lets say I have a string:
string text = "one|two|three";
If I do string[] texts = text.Split('|'); I will end up with a string array of three objects. However, this isn't what I want. What I actually want is to split the string only once... so the two arrays I could would be this:
one
two|three
Additionally, is there a way to do a single split with the last occurrence in a string? So I get:
one|two
three
As well, is there a way to split by a string, instead of a character? So I could do Split("||")

Split method takes a count as parameter, you can pass 2 in that position, which basically says that you're interested in only 2 elements maximum. You'll get the expected result.
For second question: There is no built in way AFAIK. You may need to implement it yourself by splitting all and joining first and second back.

C#'s String.Split() can take a second argument that can define the number of elements to return:
string[] texts = text.Split(new char[] { '|' }, 2);

For your first scenario, you can pass a parameter of how many strings to split into.
var text = "one|two|three";
var result = text.Split(new char[] { '|' }, 2);
Your second scenario requires a little more magic.
var text = "one|two|three";
var list = text.Split('|');
var result = new string[] { string.Join("|", list, 0, list.Length - 1), list[list.Length - 1] };
Code has not been verified to check results before using.

Well, I took it as a challenge to do your second one in one line. The result is... not pretty, mostly because it's surprisingly difficult to reverse a string and keep it as a string.
string text = "one|two|three";
var result = new String(text.Reverse().ToArray()).Split(new char[] {'|'}, 2).Reverse().Select(c => new String(c.Reverse().ToArray()));
Basically, you reverse it, then follow the same procedure as the first one, then reverse each individual one, as well as the resulting array.

You can simply do like this as well...
//To split at first occurence of '|'
if(text.Containts('|')){
beginning = text.subString(0,text.IndexOf('|'));
ending = text.subString(text.IndexOf('|');
}
//To split at last occurence of '|'
if(text.Contains('|')){
beginning = text.subString(0,text.LastIndexOf('|'));
ending = text.subString(text.LastIndexOf('|');
}

Second question was fun. I solved it this way:
string text = "one|two|three";
var result =
new []
{
string.Concat(text.ToCharArray().TakeWhile((c, i) => i <= text.LastIndexOf("|"))),
string.Concat(text.ToCharArray().SkipWhile((c, i) => i <= text.LastIndexOf("|")))
};

getting string and numbers

I got a string
string newString = "[17, Appliance]";
how can I put the 17 and Appliance in two separate variables while ignoring the , and the [ and ]?
I tried looping though it but the loop doesn't stop when it reaches the ,, not to mention it separated 1 & 7 instead of reading it as 17.

For example, you could use this:
newString.Split(new[] {'[', ']', ' ', ','}, StringSplitOptions.RemoveEmptyEntries);

This is another option, even though I wouldn't go with it, especially if you might have more than one [something, anothersomething] in the string.
But there you go:
string newString = "assuming you might [17, Appliance] have it like this";
int first = newString.IndexOf('[')+1; // location of first after the `[`
int last = newString.IndexOf(']'); // location of last before the ']'
var parts = newString.Substring(first, last-first).Split(','); // an array of 2
var int_bit = parts.First ().Trim(); // you could also go with parts[0]
var string_bit = parts.Last ().Trim(); // and parts[1]

This may not be the most performant method, but I'd go with it for ease of understanding.
string newString = "[17, Appliance]";
newString = newString.Replace("[", "").Replace("]",""); // Remove the square brackets
string[] results = newString.Split(new string[] { ", " }, StringSplitOptions.RemoveEmptyEntries); // Split the string
// If your string is always going to contain one number and one string:
int num1 = int.Parse(results[0]);
string string1 = results[1];
You'd want to include some validation to ensure your first element is indeed a number (use int.TryParse), and that there are indeed two elements returned after you split the string.

How to remove extra dots spaces from a string to build a decimal using C# Regex?

INPUT : There's string that numbers, and a string, dots and spaces. Notice that e defines a the separator between the numbers.
e.27.3.90.. .e 3.50 2.30..e2.0.1.2. .50..
OUTPUT : I want to remove all the spaces and those extra dots except for the one that makes up following and add a , before e,
,e273.90,e3502.30,e2012.50
Best catch was this How to remove extra decimal points?. But it's based on Javascript parseFloat().
I also saw this post : Convert to valid decimal data type. But that's in terms of SQL and pretty much using multiple replace().
PS: There are so many posts regarding regex in various kind. I tried to build one, but seems like no success so far.
Please propose any efficient one shot regex or ideas.
Would like to hear the performance gain/loss of this regex vs multiple replace()
Here is the code I have been gasping ;)..:
List<string> myList;
string s = "";
string s2 = "";
string str = "e.27.3.90..bl% .e 3.50 2.30. #rp.e2.0.1.2..50..y*x";
s = Regex.Replace(str, #"\b[a-df-z',\s]+", "");
myList = new List<string>(Regex.Split(s, #"[e]"));

Last str is your result
string str = "e.27.3.90..bl% .e 3.50 2.30. #rp.e2.0.1.2..50..y*x";
str = Regex.Replace(str, "[^e^0-9]", "");
str = Regex.Replace(str, "([0-9]{2}?)(e|$)", ".$1,$2");
//str = "," + str.Substring(0, str.Length - 1);

Remove all dots from the string.
Split the string into separate items at each "e".
For each item, add a dot before the last 2 digits.
Recombine the items back into one string, placing a comma between items.
These steps are easily performed with the standard String methods, but you could use regexes if you want.

C# how to pick out certain part in a string

I have a string in a masked TextBox that looks like this:
123.456.789.abc.def.ghi
"---.---.---.---.---.---" (masked TextBox format when empty, cannot use underscore X( )
Please ignore the value of the characters (they can be duplicated, and not unique as above). How can I pick out part of the string, say "789"? String.Remove() does not work, as it removes everything after the index.

You could use Split in order to separate your values if the . is always contained in your string.
string input = "123.456.789.abc.def";
string[] mySplitString = input.Split('.');
for (int i = 0; i < mySplitString.Length; i++)
{
// Do you search part here
}

Do you mean you want to obtain that part of the string? If so, you could use string.Split
string s = "123.456.789.abc.def.ghi";
var splitString = s.Split('.');
// splitString[2] will return "789"

You could simply use String.Split (if the string is actually what you have shown)
string str = "123.456.789.abc.def.ghi";
string[] parts = str.Split('.');
string third = parts.ElementAtOrDefault(2); // zero based index
if(third != null)
Console.Write(third);
I've just used Enumerable.ElementAtOrDefault because it returns null instead of an exception if there's no such index in the collection(It falls back to parts[2]).

Finding a string:
string str="123.456.789.abc.def.ghi";
int i = str.IndexOf("789");
string subStr = str.Substring(i,3);
Replacing the substring:
str = str.Replace("789","").Replace("..",".");
Regex:
str = Regex.Replace(str,"789","");
The regex can give you a lot of flexibility finding things with minimum code, the drawback is it may be difficult to write them

If you know the index of where your substring begins and the length that it will be, you can use String.Substring(). This will give you the substring:
String myString = "123.456.789";
// looking for "789", which starts at index 8 and is length 3
String smallString = myString.Substring(8, 3);
If you are trying to remove a specific part of the string, use String.Replace():
String myString = "123.456.789";
String smallString = myString.Replace("789", "");

var newstr = new String(str.where(c => "789")).tostring();..i guess this would work or you can use sumthng like this

Try using Replace.
String.Replace("789", "")

Extract the last word from a string using C#

My string is like this:
string input = "STRIP, HR 3/16 X 1 1/2 X 1 5/8 + API";
Here actually I want to extract the last word, 'API', and return.
What would be the C# code to do the above extraction?

Well, the naive implementation to that would be to simply split on each space and take the last element.
Splitting is done using an instance method on the String object, and the last of the elements can either be retrieved using array indexing, or using the Last LINQ operator.
End result:
string lastWord = input.Split(' ').Last();
If you don't have LINQ, I would do it in two operations:
string[] parts = input.Split(' ');
string lastWord = parts[parts.Length - 1];
While this would work for this string, it might not work for a slightly different string, so either you'll have to figure out how to change the code accordingly, or post all the rules.
string input = ".... ,API";
Here, the comma would be part of the "word".
Also, if the first method of obtaining the word is correct, that is, everything after the last space, and your string adheres to the following rules:
Will always contain at least one space
Does not end with one or more spaces (in case of this you can trim it)
Then you can use this code that will allocate fewer objects on the heap for GC to worry about later:
string lastWord = input.Substring(input.LastIndexOf(' ') + 1);
However, if you need to consider commas, semicolons, and whatnot, the first method using splitting is the best; there are fewer things to keep track of.

First:
using System.Linq; // System.Core.dll
then
string last = input.Split(' ').LastOrDefault();
// or
string last = input.Trim().Split(' ').LastOrDefault();
// or
string last = input.Trim().Split(' ').LastOrDefault().Trim();

var last = input.Substring(input.LastIndexOf(' ')).TrimStart();
This method doesn't allocate an entire array of strings as the others do.

string workingInput = input.Trim();
string last = workingInput.Substring(workingInput.LastIndexOf(' ')).Trim();
Although this may fail if you have no spaces in the string. I think splitting is unnecessarily intensive just for one word :)

static class Extensions
{
private static readonly char[] DefaultDelimeters = new char[]{' ', '.'};
public string LastWord(this string StringValue)
{
return LastWord(StringValue, DefaultDelimeters);
}
public string LastWord(this string StringValue, char[] Delimeters)
{
int index = StringValue.LastIndexOfAny(Delimeters);
if(index>-1)
return StringValue.Substring(index);
else
return null;
}
}
class Application
{
public void DoWork()
{
string sentence = "STRIP, HR 3/16 X 1 1/2 X 1 5/8 + API";
string lastWord = sentence.LastWord();
}
}

var lastWord = input.Split(new char[] {' '}, StringSplitOptions.RemoveEmptyEntries).Last();

string input = "STRIP, HR 3/16 X 1 1/2 X 1 5/8 + API";
var a = input.Split(' ');
Console.WriteLine(a[a.Length-1]);