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Remove all but specified substring from string

I have a string that contains several instances of a substring, as well as other text. The substring is specified by beginning with a given sequence of letters (e.g. CNTY) and ending with a double slash (//). How could I efficiently remove all text that does not fall inside the specified substring? Thanks for the help. I found that this Regex will return the result needed:
string result = Regex.Matches(text, "CNTY(.*)//").Cast<Match>().Aggregate("", (s, t) => s + t.Value, s => s);
But, I have another more complicated substring, which begins with WEATHLOC, then contains wildcard text across several lines, and ends with a line beginning RMKS, more wildcard text, and then //. Here is an example:
WEATHLOC/ICAO:KCOS//
OBSTIME/052005Z//
WIND/360/10//
VSBY/10/SM//
CLDLYR/-/LYR:BKN//
TEMP/MAXTEMP:15/MINTEMP:18//
ALTSTG/HG:29.92//
RMKS/SAMPLE//
Everything from WEATHLOC to the final // needs to be captured, and I can only rely on its beginning with WEATHLOC and ending with RMKS*//. Is there a way to express that in a Regex match?

This should work:
string text = "hiCNTYhello//content What /-CNTYworld//12texCNTY!//That's it";
string search = "CNTY(.*?)//";
MatchCollection matches = Regex.Matches(text, search);
Will match "hello", "world" and "!"

This little code segment works. The RegEx method was too difficult for me, but this does work. We are trying to check if we are in bounds of CNTY // and to output that text to the StringBuilder.
static void Main(string[] args)
{
var input = #"CNTYTestingTesting//This is some more test CNTY1234//And some moreCNTYWhat is this?//";
var sb = new StringBuilder();
int inCnty = -1;
for (int i = 0; i < input.Length; i ++)
{
// Test for start
if (i < input.Length - 4)
{
if (input.Substring(i, 4) == "CNTY")
{
inCnty = i + 4; // Index of first CNTY
}
}
// Test for end
if (i < input.Length - 1)
{
if (input.Substring(i, 2) == #"//")
{
inCnty = -1; // Reset
}
}
// Test if we are in the segment
if (i >= inCnty && inCnty > 0)
{
// Outside string
sb.Append(input[i]);
}
}
var output = sb.ToString();
Console.WriteLine(output);
Console.Read();
}

Reverse Words at odd position only C#

This is my code. How can I edit it to show every word which is at the odd position ONLY to be reversed?
for (int i = input.Length - 1; i >= 0; i--)
{
if (input[i] == ' ')
{
result = tmp + " " + result;
tmp = "";
}
else
tmp += input[i];
}
result = tmp + " " + result;
Console.WriteLine(result);
Example input:
"How are you today"
to output:
"How era you yadot"
Based on the position of a word ['How' -> 0] do not reverse; [are -> 1 odd index] Reverse

You can achieve it with the help of LINQ:
var input = "hello this is a test message";
var inputWords = input.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
var result = string.Join(" ",
inputWords.Select((w, i) =>
i % 2 == 0
? w
: new string(w.Reverse().ToArray())
));
Where w in the select is the word, and i is the index, starting at 0 for the first word. % is the modulus operator and gets the remainder. If i % 2 == 0 (i.e. i can be divided by 2 with no remainder), then the original is returned. If there is a remainder (odd) then the reversed word is returned. Finally, it's all wrapped up in a string.Join(" ", items); which turns it back into a normal string rather than an array of items.
Try it online

So far you have a string, like this:
string input = "I want to reverse all odd words (odd words only!).";
And you, naturally, want to perform the task. Now it's the main question what's an odd word?
If you mean word's position (I at position 0, want at 1 - should be reversed etc.)
then you can use regular expressions to match words and Linq to process them:
using System.Linq; // To reverse single word
using System.Text.RegularExpressions; // To match the words within the text
...
// Let's elaborate the test example: add
// 1. some punctuation - ()!. - to preserve it
// 2. different white spaces (spaces and tabulation - \t)
// to add difficulties for naive algorithms
// 3. double spaces (after "to") to mislead split based algorithms
string input = "I want to reverse all\todd words (odd words only!).";
int index = 0; // words' indexes start from zero
string result = Regex.Replace(
input,
"[A-Za-z']+", // word is letters and apostrophes
match => index++ % 2 == 0
? match.Value // Even words intact
: string.Concat(match.Value.Reverse())); // Odd words reversed
Console.WriteLine(result);
If you want to reverse the words with odd Length, i.e. I, all, odd then all you have to do is to change the condition to
match => match.Value % 2 == 0
Outcome:
I tnaw to esrever all ddo words (ddo words ylno!).
Please, notice, that the punctuation has been preserved (only words are reversed).

OP: Based on the position of a word ['How' -> 0] do not reverse; [are -> 1 odd index] Reverse
public static void Main()
{
string input = "How are you today Laken-C";
//As pointed out by #Dmitry Bychenko string input = "How are you today";
//(double space after How) leads to How are uoy today outcome
input = Regex.Replace(input, #"\s+", " ");
var inp = input.Split(' ').ToList();
for (int j = 0; j < inp.Count(); j++)
{
if(j % 2 == 1)
{
Console.Write(inp[j].Reverse().ToArray());
Console.Write(" ");
}
else
Console.Write(inp[j] + " ");
}
}
OUTPUT:
DEMO:
dotNetFiddle

try this is perfect working code..
static void Main(string[] args)
{
string orgstr = "my name is sagar";
string revstr = "";
foreach (var word in orgstr.Split(' '))
{
string temp = "";
foreach (var ch in word.ToCharArray())
{
temp = ch + temp;
}
revstr = revstr + temp + " ";
}
Console.Write(revstr);
Console.ReadKey();
}
Output: ym eman si ragas

How to capitalize the first character of every sentence

Create an application with a method that accepts a string as an argument and returns a copy of the string with the first character of each sentence capitalized.
This is what I have to far and I can't seem to get it right:
//Create method to process string.
private string Sentences(string input)
{
//Capitalize first letter of input.
char firstLetter = char.ToUpper(input[0]);
//Combine the capitalize letter with the rest of the input.
input = firstLetter.ToString() + input.Substring(1);
//Create a char array to hold all characters in input.
char[] letters = new char[input.Length];
//Read the characters from input into the array.
for (int i = 0; i < input.Length; i++)
{
letters[i] = input[i];
}
//Loop through array to test for punctuation and capitalize a character 2 index away.
for (int index = 0; index < letters.Length; index++)
{
if(char.IsPunctuation(letters[index]))
{
if (!((index + 2) >= letters.Length))
{
char.ToUpper(letters[index+ 2]);
}
}
}
for(int ind = 0; ind < letters.Length; ind++)
{
input += letters[ind].ToString();
}
return input;
}

You could use Linq.Aggregate n - see comments in code and code output for explanation how it work's.
This one will respect "Bla. blubb" as well - you need to check for whitespaces after ".?!"
using System;
using System.Linq;
internal class Program
{
static string Capitalize(string oldSentence )
{
return
// this will look at oldSentence char for char, we start with a
// new string "" (the accumulator, short acc)
// and inspect each char c of oldSentence
// comment all the Console.Writelines in this function, thats
// just so you see whats done by Aggregate, not needed for it to
// work
oldSentence
.Aggregate("", (acc, c) =>
{
System.Console.WriteLine("Accumulated: " + acc);
System.Console.WriteLine("Cecking: " + c);
// if the accumulator is empty or the last character of
// trimmed acc is a ".?!" we append the
// upper case of c to it
if (acc.Length == 0 || ".?!".Any(p => p == acc.Trim().Last())) // (*)
acc += char.ToUpper(c);
else
acc += c; // else we add it unmodified
System.Console.WriteLine($"After: {acc}\n");
return acc; // this returns the acc for the next iteration/next c
});
}
static void Main(string[] args)
{
Console.SetBufferSize(120, 1000);
var oldSentence = "This is a testSentence. some occurences "
+ "need capitalization! for examlpe here. or here? maybe "
+ "yes, maybe not.";
var newSentence = Capitalize(oldSentence);
Console.WriteLine(new string('*', 80));
Console.WriteLine(newSentence);
Console.ReadLine();
}
}
(*)
".?!".Any(p => p == ... )) means does the string ".?!" contain any character that equals ...
acc.Trim().Last() means: remove whitespaces in front/on end of acc and give me the last character
.Last() and .Any() are also Linq. Most of the Linq-esc extension can be found here: https://msdn.microsoft.com/en-us/library/9eekhta0(v=vs.110).aspx
Output (snipped - its rather longish ;o)
Accumulated:
Cecking: T
After: T
Accumulated: T
Cecking: h
After: Th
Accumulated: Th
Cecking: i
After: Thi
Accumulated: Thi
Cecking: s
After: This
Accumulated: This
Cecking:
After: This
Accumulated: This
Cecking: i
After: This i
Accumulated: This i
Cecking: s
After: This is
<snipp - .. you get the idea how Aggregate works ...>
Accumulated: This is a testSentence.
Cecking: s
After: This is a testSentence. S
<snipp>
Accumulated: This is a testSentence. Some occurences need capitalization!
Cecking: f
After: This is a testSentence. Some occurences need capitalization! F
<snipp>
********************************************************************************
This is a testSentence. Some occurences need capitalization! For examlpe here. Or here? Maybe yes, maybe not.

I would suggest to use a regex to identify all the dots in your sentence. Get the match, make it upper case and replace it back in the original sentence, in the match index. I dont actually have any IDE in which try the code on .NET right now but i can write it in pseudocode for better understanding.
String setence = "your.setence.goes.here";
Regex rx = new Regex("/\..*?[A-Z]/");
foreach (Match match in rx.Matches(sentence))
{
setence.remove(match.Index, 2).insert(match.Index, String.ToUpper(match.Value));
}

You have two tasks:
1) Split text into sentences
2) Capitalize the first char in the sentences
Task one can be very complex, e.g. because there a lot of crazy languages out there. Put since this is homework I assume you can go ahead and simply split by well know separators.
Task two is just about basic string operations. You select the first char, make it uppercase and add the missing part of the sentence via a substring operation.
Here is a code example:
char[] separators = new char[] { '!', '.', '?' };
string[] sentencesArray = "First sentence. second sentence!lastone.".Split(separators, StringSplitOptions.RemoveEmptyEntries);
var i = 0;
Array.ForEach(sentencesArray, e =>
{
sentencesArray[i] = e.Trim().First().ToString().ToUpper() +
e.Trim().Substring(1);
i++;
});

I Have created a method in Groovy for the same
String capitalizeFirstCharInSentence(String str) {
String result = ''
str = str.toLowerCase()
List<String> strings = str.tokenize('.')
strings.each { line ->
StringBuilder builder = new StringBuilder(line)
int i = 0
while (i < builder.size() - 1 && !Character.isLowerCase(builder.charAt(i))) {
i++
}
if (Character.isLowerCase(builder.charAt(i))) {
builder.setCharAt(i, builder.charAt(i).toUpperCase())
result += builder.toString() + '.'
}
}
return result
}

I liked the way you formatted your method because it made it easy for newer coders to read so I decided to try to make the code work while maintaining the structure. The main problem I saw was that you were not replacing the arrays after formatting them.
//Create method to process string.
private string Sentences(string input)
{
//Create a char array to hold all characters in input.
char[] letters = new char[input.Length];
//Read the characters from input into the array.
for (int i = 0; i < input.Length; i++)
{
letters[i] = input[i];
}
//Capitalize first letter of input.
letters[0] = char.ToUpper(letters[0]);
//Loop through array to test for punctuation and capitalize a character 2 index away.
for (int index = 0; index < letters.Length; index++)
{
if(char.IsPunctuation(letters[index]))
{
if (index + 2 <= letters.Length)
{
letters[index + 2] = char.ToUpper(letters[index+ 2]);
}
}
}
// convert array back to string
string results = new string(letters)
return results;
}

how to extract a negative symbol from text

Below I have a piece of code that is able to extract the number values from a piece of text. So if I have string +12 is on same day, then it will extract 12.
However if I have a negative number like -12 is on the same day, I want it to extract -12, not 12.
How I can extract the minus symbol?
foreach (char c in alternativeAirportPrice.Text)
{
if (char.IsNumber(c))
{
string test = "-12 on same day";
string alternativeAirportPriceValue = string.Join("", test.ToCharArray()
.Where(x => char.IsDigit(x)).ToArray());
return alternativeAirportPriceValue;
}
}

You can use a regex pattern:
-?\d+
This will match any string of digits or a - followed by a string of digits.
string text = "-12 on the same day";
var match = Regex.Match(text, "-?\\d+");
return match.Value;
Remember to add a using directive to System.Text.RegularExpressions!

This should be what you want based on the question's desired result. Note that you don't need a foreach loop for this purpose just LINQ is enough:
string.Join("", test.Split(' ').Where(x => int.TryParse(x , out _)).ToArray());
return alternativeAirportPriceValue;

Try this:
public IEnumerable<int> ExtractNumbers(string text)
{
text += " ";
var temp = string.Empty;
for (var i = 0; i < text.Length; i++)
{
if (char.IsDigit(text[i]))
{
if ('-'.Equals(text[i - 1]))
{
temp += text[i - 1];
}
temp += text[i];
}
else if (temp.Length > 0)
{
yield return int.Parse(temp);
temp = string.Empty;
}
}
}
This way you can handle cases where the string has multiple numbers in it, as observed by #Sir Rufo
The line:
text += " ";
is there to ensure the loop will hit the "else if" block when a number is in the last position of the string, e.g. "-12 on the same day 123456"

Adding a '-' to my string in C#

I Have a string in the form "123456789".
While displaying it on the screen I want to show it as 123-456-789.
Please let me knwo how to add the "-" for every 3 numbers.
Thanks in Advance.

You can use string.Substring:
s = s.Substring(0, 3) + "-" + s.Substring(3, 3) + "-" + s.Substring(6, 3);
or a regular expression (ideone):
s = Regex.Replace(s, #"\d{3}(?=\d)", "$0-");

I'll go ahead and give the Regex based solution:
string rawNumber = "123456789";
var formattedNumber = Regex.Replace(rawNumber, #"(\d{3}(?!$))", "$1-");
That regex breaks down as follows:
( // Group the whole pattern so we can get its value in the call to Regex.Replace()
\d // This is a digit
{3} // match the previous pattern 3 times
(?!$) // This weird looking thing means "match anywhere EXCEPT the end of the string"
)
The "$1-" replacement string means that whenever a match for the above pattern is found, replace it with the same thing (the $1 part), followed by a -. So in "123456789", it would match 123 and 456, but not 789 because it's at the end of the string. It then replaces them with 123- and 456-, giving the final result 123-456-789.

You can use for loop also if the string length is not fixed to 9 digits as follows
string textnumber = "123456789"; // textnumber = "123456789012346" also it will work
string finaltext = textnumber[0]+ "";
for (int i = 1; i < textnumber.Length; i++)
{
if ((i + 1) % 3 == 0)
{
finaltext = finaltext + textnumber[i] + "-";
}
else
{
finaltext = finaltext + textnumber[i];
}
}
finaltext = finaltext.Remove(finaltext.Length - 1);