We Keep Coding

LINQ: Null checking in string.Format()

I have a requirement to get the first letter of the first, middle and last names. It is working if each of the fields contain value. But the middle name is nullable field. So i'm getting error if the value of middle name is null.
(from P in this._dbContext.Person
where P.PersonIndex == personIndex
select new PersonInitialsDTO
{
PersonIndex = P.PersonIndex,
PersonInitials = string.Format("{0}{1}{2}", P.FirstName.ToUpper().First(), P.MiddleName.ToUpper().First(), P.LastName.ToUpper().First())
}).FirstOrDefault();

use ? to see if the value is null before executing next methods.
string.Format("{0}{1}{2}", P.FirstName.ToUpper().First(), P.MiddleName?.ToUpper().First(), P.LastName.ToUpper().First())
P.MiddleName?.ToUpper().First() -> If P.MiddleName is null, dont do ToUpper() or any other methods afterwards.
Example of use of ?. in string.format statement.
Pers person = new Pers()
{
First = "First",
Last = "Last"
};
Console.WriteLine(string.Format("{0}{1}{2}", person.First.First(), person.Middle?.ToUpper().First(), person.Last.First()));
// Prints
FL

Requirement: get the first letter of the first, middle and last names.
Well, apparently this requirement is not complete: if one of these names is null or empty, there is no first letter.
Furthermore: if I look at the code, you don't want the first letter, you want a string that contains the first letter.
And why uppercase the complete string if you will only use the first character?
So let's change it slightly:
Requirement: Given three strings: first, middle and last, get me the string that contains the uppercase values of the first character of each of these strings, or String.Empty if the string is null or empty.
"Vincent" "van" "Gogh" => "VVG"
"rembrandt" "van" "rijn" => "RVR"
"Piet" "Mondriaan" => "PM"
From each of these three strings,
Check if if it is null, if so, use Enumerable.Empty<char>
Create a sequence that contains only the first character of the string. So if the string was null or empty, this first character will be an empty sequence of character).
Concatenate these three sequences.
Result: a sequence of characters that contains only the first character of each of these strings, or no character at all if the string was null or empty.
In baby steps, I'll write the type in front, so you can see what happens.
string first = ...
string middle = ...
string last = ...
IEnumerable<char> firstChars = first?.Take(1) ?? Enumerable.Empty<char>(),
IEnumerable<char> midChars = middle?.Take(1) ?? Enumerable.Empty<char>(),
IEnumerable<char> lastChars = last?.Take(1) ?? Enumerable.Empty<char>(),
IEnumerable<char> chars = firstChars.Concat(midChars).Concat(lastChars);
So from our original input examples we have:
Vincent Van Gogh: {'V', 'V', 'G'}
rembrandt van rijn: {'r', 'v', 'r'}
Piet Mondriaan {'p', 'm'}
So all we have to do is to convert them to uppercase and convert to a string:
IEnumerable uppercaseChars = chars.Select(c => Char.ToUpper(c));
Note: until know the query is not executed! I only used methods that use deferred execution!
string result = new string(uppercaseChars.ToArray());
Of course you can write this in one big LINQ statement. I'm not sure if that would improve readability. It won't have any effect on performance.

I tried with below. Now it's working
(from P in this._dbContext.Person
where P.PersonIndex == personIndex
select new PersonInitialsDTO
{
PersonIndex = P.PersonIndex,
PersonInitials = (P.MiddleName == "")
? string.Format("{0}{1}", P.FirstName.ToUpper().First(),
P.LastName.ToUpper().First())
: string.Format("{0}{1}{2}", P.FirstName.ToUpper().First(),
P.MiddleName.ToUpper().First(), P.LastName.ToUpper().First())
}).FirstOrDefault();

Remove a value from comma separated string in C#

I have done something like:
var a = "77,82,83";
foreach (var group in a.Split(','))
{
a = group.Replace("83", string.Empty);
}
If i want to remove 83 but override last updated value and got output empty or remove value from that i passed to replace.
e.g var a = 77,82,83
want output like 77,82
Edit:
"83" can be in any position.

If you want output as string you don't need to Split. Just get the LastIndexOf the , character and perform Substring on the variable:
var a = "77,82,83";
var newString = a.Substring(0, a.LastIndexOf(',')); // 77,82
If you are unsure if the string has at least one ,, you can validate before performing a Substring:
var a = "77,82,83";
var lastIndex = a.LastIndexOf(',');
if (lastIndex > 0)
var newString = a.Substring(0, lastIndex);
Update:
If you want to remove specific values from any position:
Split the string -> Remove the values using Where -> Join them with , separator
a = string.Join(",", a.Split(',').Where(i => i != "83"));
Here's a fiddle

You might need to clarify the question slightly but I think you're asking for the following:
var a = "72,82,83";
var group = a.Split(',').ToList();
int position = group.FindIndex(p => p.Contains("83"));
group.RemoveAt(position);
You can make the item you're looking for in the Contains query a parameter.
I think the problem you're having with your original code is that the foreach is a loop over each item in the array, so you're trying to remove "83" on each pass.

How to contact whole text from file into the string avoiding empty lines beetwen strings

How to get whole text from document contacted into the string. I'm trying to split text by dot: string[] words = s.Split('.'); I want take this text from text document. But if my text document contains empty lines between strings, for example:
pat said, “i’ll keep this ring.”
she displayed the silver and jade wedding ring which, in another time track,
she and joe had picked out; this
much of the alternate world she had elected to retain. he wondered what - if any - legal basis she had kept in addition. none, he hoped; wisely, however, he said nothing. better not even to ask.
result looks like this:
1. pat said ill keep this ring
2. she displayed the silver and jade wedding ring which in another time track
3. she and joe had picked out this
4. much of the alternate world she had elected to retain
5. he wondered what if any legal basis she had kept in addition
6. none he hoped wisely however he said nothing
7. better not even to ask
but desired correct output should be like this:
1. pat said ill keep this ring
2. she displayed the silver and jade wedding ring which in another time track she and joe had picked out this much of the alternate world she had elected to retain
3. he wondered what if any legal basis she had kept in addition
4. none he hoped wisely however he said nothing
5. better not even to ask
So to do this first I need to process text file content to get whole text as single string, like this:
pat said, “i’ll keep this ring.” she displayed the silver and jade wedding ring which, in another time track, she and joe had picked out; this much of the alternate world she had elected to retain. he wondered what - if any - legal basis she had kept in addition. none, he hoped; wisely, however, he said nothing. better not even to ask.
I can't to do this same way as it would be with list content for example: string concat = String.Join(" ", text.ToArray());,
I'm not sure how to contact text into string from text document

I think this is what you want:
var fileLocation = #"c:\\myfile.txt";
var stringFromFile = File.ReadAllText(fileLocation);
//replace Environment.NewLine with any new line character your file uses
var withoutNewLines = stringFromFile.Replace(Environment.NewLine, "");
//modify to remove any unwanted character
var withoutUglyCharacters = Regex.Replace(withoutNewLines, "[“’”,;-]", "");
var withoutTwoSpaces = withoutUglyCharacters.Replace(" ", " ");
var result = withoutTwoSpaces.Split('.').Where(i => i != "").Select(i => i.TrimStart()).ToList();
So first you read all text from your file, then you remove all unwanted characters and then split by . and return non empty items

Have you tried replacing double new-lines before splitting using a period?
static string[] GetSentences(string filePath) {
if (!File.Exists(filePath))
throw new FileNotFoundException($"Could not find file { filePath }!");
var lines = string.Join("", File.ReadLines(filePath).Where(line => !string.IsNullOrEmpty(line) && !string.IsNullOrWhiteSpace(line)));
var sentences = Regex.Split(lines, #"\.[\s]{1,}?");
return sentences;
}
I haven't tested this, but it should work.
Explanation:
if (!File.Exists(filePath))
throw new FileNotFoundException($"Could not find file { filePath }!");
Throws an exception if the file could not be found. It is advisory you surround the method call with a try/catch.
var lines = string.Join("", File.ReadLines(filePath).Where(line => !string.IsNullOrEmpty(line) && !string.IsNullOrWhiteSpace(line)));
Creates a string, and ignores any lines which are purely whitespace or empty.
var sentences = Regex.Split(lines, #".[\s]{1,}?");
Creates a string array, where the string is split at every period and whitespace following the period.
E.g:
The string "I came. I saw. I conquered" would become
I came
I saw
I conquered
Update:
Here's the method as a one-liner, if that's your style?
static string[] SplitSentences(string filePath) => File.Exists(filePath) ? Regex.Split(string.Join("", File.ReadLines(filePath).Where(line => !string.IsNullOrEmpty(line) && !string.IsNullOrWhiteSpace(line))), #"") : null;

I would suggest you to iterate through all characters and just check if they are in range of 'a' >= char <= 'z' or if char == ' '. If it matches the condition then add it to the newly created string else check if it is '.' character and if it is then end your line and add another one :
List<string> lines = new List<string>();
string line = string.Empty;
foreach(char c in str)
{
if((char.ToLower(c) >= 'a' && char.ToLower(c) <= 'z') || c == 0x20)
line += c;
else if(c == '.')
{
lines.Add(line.Trim());
line = string.Empty;
}
}
Working online example
Or if you prefer "one-liner"s :
IEnumerable<string> lines = new string(str.Select(c => (char)(((char.ToLower(c) >= 'a' && char.ToLower(c) <= 'z') || c == 0x20) ? c : c == '.' ? '\n' : '\0')).ToArray()).Split('\n').Select(s => s.Trim());

I may be wrong about this. I would think that you may not want to alter the string if you are splitting it. Example, there are double/single quote(s) (“) in part of the string. Removing them may not be desired which brings up the possibly of a question, reading a text file that contains single/double quotes (as your example data text shows) like below:
var stringFromFile = File.ReadAllText(fileLocation);
will not display those characters properly in a text box or the console because the default encoding using the ReadAllText method is UTF8. Example the single/double quotes will display (replacement characters) as diamonds in a text box on a form and will be displayed as a question mark (?) when displayed to the console. To keep the single/double quotes and have them display properly you can get the encoding for the OS’s current ANSI encoding by adding a parameter to the ReadAllText method like below:
string stringFromFile = File.ReadAllText(fileLocation, ASCIIEncoding.Default);
Below is code using a simple split method to .split the string on periods (.) Hope this helps.
private void button1_Click(object sender, EventArgs e) {
string fileLocation = #"C:\YourPath\YourFile.txt";
string stringFromFile = File.ReadAllText(fileLocation, ASCIIEncoding.Default);
string bigString = stringFromFile.Replace(Environment.NewLine, "");
string[] result = bigString.Split('.');
int count = 1;
foreach (string s in result) {
if (s != "") {
textBox1.Text += count + ". " + s.Trim() + Environment.NewLine;
Console.WriteLine(count + ". " + s.Trim());
count++;
}
else {
// period at the end of the string
}
}
}

Stopwords removing from string

I am trying to remove the stopwords from string but the problem is it is removing the characters from the single words if it is appearing again in the string.
For example the original string is:
"this movie good."
the resulted string is:
"this movie good.". works fine.but
If the string is: "this movie is good."
then resulted string will be: "th movie good."
As is repeating in this string so it is exempted in the result.
Another string:
"this game is fantastic. So, I watched and played a lot."
result: "gme fntstic. So, wtched plyed lot."
As a repeated in this string thus resulted string show all words exempting a.
I am sing this code:
List<string> stopWordsList = new List<string>();
stopWordsList = stopWordsFilter();//funtion returning the list of stop words taking from file.
string propertyValue = "this game is fantastic. So, I watched and played a lot.";
foreach (string word1 in propertyValue.Split(' '))
{
foreach ( var word in stopWordsList)
{
if (word.Equals(word1) && word.Length == word1.Length)
{
propertyValue = propertyValue.Replace(word, "");
}
}
}
Console.WriteLine(propertyValue);

The problem is that you replace the stop-word with String.Empty. String.Replace doesn't care about words but substrings.
You could use this approach:
string propertyValue = "this game is fantastic. So, I watched and played a lot.";
var words = propertyValue.Split();
var newWords = words.Except(stopWordsFilter);
propertyValue = string.Join(" ", newWords);
If you want to ignore the case, so omit also "Is":
var newWords = words.Except(stopWordsFilter, StringComparer.InvariantCultureIgnoreCase);

I propose here a solution that uses linq:
string result = propertyValue.Split(' ')
.Where(s => !stopWordsList.Contains(s))
.Aggregate((current, next) => current + " " + next);
Console.WriteLine(result);

C# how to split a string backwards?

What i'm trying to do is split a string backwards. Meaning right to left.
string startingString = "<span class=\"address\">Hoopeston,, IL 60942</span><br>"
What I would do normally is this.
string[] splitStarting = startingString.Split('>');
so my splitStarting[1] would = "Hoopeston,, IL 60942</span"
then I would do
string[] splitAgain = splitStarting[1].Split('<');
so splitAgain[0] would = "Hoopeston,, IL 60942"
Now this is what I want to do, I want to split by ' ' (a space) reversed for the last 2 instances of ' '.
For example my array would come back like so:
[0]="60942"
[1]="IL"
[2] = "Hoopeston,,"
To make this even harder I only ever want the first two reverse splits, so normally I would do something like this
string[] splitCity,Zip = splitAgain[0].Split(new char[] { ' ' }, 3);
but how would you do that backwards? The reason for that is, is because it could be a two name city so an extra ' ' would break the city name.

Regular expression with named groups to make things so much simpler. No need to reverse strings. Just pluck out what you want.
var pattern = #">(?<city>.*) (?<state>.*) (?<zip>.*?)<";
var expression = new Regex(pattern);
Match m = expression .Match(startingString);
if(m.success){
Console.WriteLine("Zip: " + m.Groups["zip"].Value);
Console.WriteLine("State: " + m.Groups["state"].Value);
Console.WriteLine("City: " + m.Groups["city"].Value);
}
Should give the following results:
Found 1 match:
1. >Las Vegas,, IL 60942< has 3 groups:
1. Las Vegas,, (city)
2. IL (state)
3. 60942 (zip)
String literals for use in programs:
C#
#">(?<city>.*) (?<state>.*) (?<zip>.*?)<"

One possible solution - not optimal but easy to code - is to reverse the string, then to split that string using the "normal" function, then to reverse each of the individual split parts.
Another possible solution is to use regular expressions instead.

I think you should do it like this:
var s = splitAgain[0];
var zipCodeStart = s.LastIndexOf(' ');
var zipCode = s.Substring(zipCodeStart + 1);
s = s.Substring(0, zipCodeStart);
var stateStart = s.LastIndexOf(' ');
var state = s.Substring(stateStart + 1);
var city = s.Substring(0, stateStart );
var result = new [] {zipCode, state, city};
Result will contain what you requested.

If Split could do everything there would be so many overloads that it would become confusing.
Don't use split, just custom code it with substrings and lastIndexOf.
string str = "Hoopeston,, IL 60942";
string[] parts = new string[3];
int place = str.LastIndexOf(' ');
parts[0] = str.Substring(place+1);
int place2 = str.LastIndexOf(' ',place-1);
parts[1] = str.Substring(place2 + 1, place - place2 -1);
parts[2] = str.Substring(0, place2);

You can use a regular expression to get the three parts of the string inside the tag, and use LINQ extensions to get the strings in the right order.
Example:
string startingString = "<span class=\"address\">East St Louis,, IL 60942</span><br>";
string[] city =
Regex.Match(startingString, #"^.+>(.+) (\S+) (\S+?)<.+$")
.Groups.Cast<Group>().Skip(1)
.Select(g => g.Value)
.Reverse().ToArray();
Console.WriteLine(city[0]);
Console.WriteLine(city[1]);
Console.WriteLine(city[2]);
Output:
60942
IL
East St Louis,,

How about
using System.Linq
...
splitAgain[0].Split(' ').Reverse().ToArray()
-edit-
ok missed the last part about multi word cites, you can still use linq though:
splitAgain[0].Split(' ').Reverse().Take(2).ToArray()
would get you the
[0]="60942"
[1]="IL"
The city would not be included here though, you could still do the whole thing in one statement but it would be a little messy:
var elements = splitAgain[0].Split(' ');
var result = elements
.Reverse()
.Take(2)
.Concat( new[ ] { String.Join( " " , elements.Take( elements.Length - 2 ).ToArray( ) ) } )
.ToArray();
So we're
Splitting the string,
Reversing it,
Taking the two first elements (the last two originally)
Then we make a new array with a single string element, and make that string from the original array of elements minus the last 2 elements (Zip and postal code)
As i said, a litle messy, but it will get you the array you want. if you dont need it to be an array of that format you could obviously simplfy the above code a little bit.
you could also do:
var result = new[ ]{
elements[elements.Length - 1], //last element
elements[elements.Length - 2], //second to last
String.Join( " " , elements.Take( elements.Length - 2 ).ToArray( ) ) //rebuild original string - 2 last elements
};

At first I thought you should use Array.Reverse() method, but I see now that it is the splitting on the ' ' (space) that is the issue.
Your first value could have a space in it (ie "New York"), so you dont want to split on spaces.
If you know the string is only ever going to have 3 values in it, then you could use String.LastIndexOf(" ") and then use String.SubString() to trim that off and then do the same again to find the middle value and then you will be left with the first value, with or without spaces.

Was facing similar issue with audio FileName conventions.
Followed this way: String to Array conversion, reverse and split, and reverse each part back to normal.
char[] addressInCharArray = fullAddress.ToCharArray();
Array.Reverse(addressInCharArray);
string[] parts = (new string(addressInCharArray)).Split(new char[] { ' ' }, 3);
string[] subAddress = new string[parts.Length];
int j = 0;
foreach (string part in parts)
{
addressInCharArray = part.ToCharArray();
Array.Reverse(addressInCharArray);
subAddress[j++] = new string(addressInCharArray);
}