Develop Reference

remove url from a given string in c#

I tried doing this
using System;
using System.Collections.Generic;
using System.Text;
namespace UrlsDetector
{
class UrlDetector
{
public static string RemoveUrl(string input)
{
var words = input;
while(words.Contains("https://"))
{
string urlToRemove = words.Substring("https://", #" ");
words = words.Replace("https://" + urlToRemove , #"");
}
}
}
class Program
{
static void Main()
{
Console.WriteLine(UrlDetector.RemoveUrl(
"I saw a cat and a horse on https://www.youtube.com/"));
}
}
}
but it doesn't work
what I want to achieve is remove the entire "https://www.youtube.com/" and display "I saw a cat and a horse on"
I also want to display a message like "the sentence you input doesn't have url" if the sentence doesn't have any url. but as you can I didnt put any code to do that I just need to fix this code first but if you want to help me do that too, I gladly appreciated it.
thanks for responses.

If you are looking for a non RegEx way to do this, here you go. But the method I encoded below assumes that a URL begins with "http://" or "https://", which means it will not work with URL's that begin with something like ftp:// or file://, although the code below can be easily modified to support that. Also, it assumes the URL path continues until it reaches either the end of the string or a white space character (like a space or a tab or a new line). Again, this can easily be modified if your requirements are different.
Also, if the string contains no URL, currently it just returns a blank string. You can modify this easily too!
using System;
public class Program
{
public static void Main()
{
string str = "I saw a cat and a horse on https://www.youtube.com/";
UrlExtraction extraction = RemoveUrl(str);
Console.WriteLine("Original Text: " + extraction.OriginalText);
Console.WriteLine();
Console.WriteLine("Url: " + extraction.ExtractedUrl);
Console.WriteLine("Text: " + extraction.TextWithoutUrl);
}
private static UrlExtraction RemoveUrl(string str)
{
if (String.IsNullOrWhiteSpace(str))
{
return new UrlExtraction("", "", "");
}
int startIndex = str.IndexOf("https://",
StringComparison.InvariantCultureIgnoreCase);
if (startIndex == -1)
{
startIndex = str.IndexOf("http://",
StringComparison.InvariantCultureIgnoreCase);
}
if (startIndex == -1)
{
return new UrlExtraction(str, "", "");
}
int endIndex = startIndex;
while (endIndex < str.Length && !IsWhiteSpace(str[endIndex]))
{
endIndex++;
}
return new UrlExtraction(str, str.Substring(startIndex, endIndex - startIndex),
str.Remove(startIndex, endIndex - startIndex));
}
private static bool IsWhiteSpace(char c)
{
return
c == '\n' ||
c == '\r' ||
c == ' ' ||
c == '\t';
}
private class UrlExtraction
{
public string ExtractedUrl {get; set;}
public string TextWithoutUrl {get; set;}
public string OriginalText {get; set;}
public UrlExtraction(string originalText, string extractedUrl,
string textWithoutUrl)
{
OriginalText = originalText;
ExtractedUrl = extractedUrl;
TextWithoutUrl = textWithoutUrl;
}
}
}

A simplified version of what you're doing. Instead of using SubString or IndexOf, I split the input into a list of strings, and remove the items that contain a URL. I iterate over the list in reverse as removing an item in a forward loop direction will skip an index.
public static string RemoveUrl(string input)
{
List<string> words = input.Split(" ").ToList();
for (int i = words.Count - 1; i >= 0; i--)
{
if (words[i].StartsWith("https://")) words.RemoveAt(i);
}
return string.Join(" ", words);
}
This methods advantage is avoiding SubString and Replace methods that essentially create new Strings each time they're used. In a loop this excessive string manipulation can put pressure on the Garbage Collector and bloat the Managed Heap. A Split and Join has less performance cost in comparison especially when used in a loop like this with a lot of data.
#Moshi is correct with large amounts of data, so this is more of a Production Code Base example:
public static class Ext
{
public static LinkedList<T> RemoveAll<T>(this LinkedList<T> list, Predicate<T> match)
{
if (list == null)
{
throw new ArgumentNullException("list");
}
if (match == null)
{
throw new ArgumentNullException("match");
}
var count = 0;
var node = list.First;
while (node != null)
{
var next = node.Next;
if (match(node.Value))
{
list.Remove(node);
count++;
}
node = next;
}
return list;
}
}
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
var s= "I saw a https://www.youtube.com/cat and a https://www.youtube.com/horse on https://www.youtube.com/";
//Uncomment for second run
//s= #"I saw a https://www.youtube.com/cat and a https://www.youtube.com/horse on https://www.youtube.com/
//but it doesnt work
//what I want to achieve is remove the entire https://www.youtube.com/ and display I saw a cat and a horse on
//I also want to display a message like the sentence you input doesn't have url if the sentence doesn't have any url. but as you can I didnt put any code to do that I just need to fix this code first but if you want to help me do that too, I gladly appreciated it.
//thanks for responses.";
Stopwatch watch = new Stopwatch();
watch.Start();
var resultList = RemoveUrl(s);
watch.Stop(); Debug.WriteLine(watch.Elapsed.ToString());
watch.Reset(); watch.Start();
var wordsLL = new LinkedList<string>(s.Split(' '));
var result = string.Join(' ', wordsLL.RemoveAll(x => x.StartsWith("https://")));
watch.Stop(); Debug.WriteLine(watch.Elapsed.ToString());
}
}
var s one line:
watch.Elapsed = {00:00:00.0116388}
watch.Elapsed = {00:00:00.0134778}
var s multilines:
watch.Elapsed = {00:00:00.0013588}
watch.Elapsed = {00:00:00.0009252}

Using basic string manipulation will never get you where you want to be.
Using regular expressions makes this very easy for you.
search for a piece of text that looks like
"http(s)?:\/\/\S*[^\s\.]":
http: the text block http
(s)?: the optional (?) letter s
:\/\/: the characters ://
\S*: any amount (*) non white characters (\S)
[^\s\.]: any character that is not (^) in the list ([ ]) of characters being white characters (\s) or dot (\.). This allows you to exclude the dot at the end of a sentence from your url.
using System;
using System.Text.RegularExpressions;
namespace UrlsDetector
{
internal class Program
{
static void Main(string[] args)
{
Console.WriteLine(UrlDetector.RemoveUrl(
"I saw a cat and a horse on https://www.youtube.com/ and also on http://www.example.com."));
Console.ReadLine();
}
}
class UrlDetector
{
public static string RemoveUrl(string input)
{
var regex = new Regex($#"http(s)?:\/\/\S*[^\s.]");
return regex.Replace(input, "");
}
}
}
Using regular expressions you can also detect matches Regex.Match(...) which allows you to detect any urls in your text.

Better way to use, split and StringBuilder. Code will be look like this. StringBuilder is optimized this kind of situation.
Pseudocode:
var words = "I saw a cat and a horse on https://www.youtube.com/".Split(" ").ToList();
var sb = new StringBuilder();
foreach(var word in words){
if(!word.StartsWith("https://")) sb.Append(word + " ");
}
return sb.ToString();

Don't split by escaped string - C# [duplicate]

This question already has answers here:
How can I Split(',') a string while ignore commas in between quotes?
(3 answers)
C# Regex Split - commas outside quotes
(7 answers)
Closed 5 years ago.
I need to split a csv file by comma apart from where the columns is between quote marks. However, what I have here does not seem to be achieving what I need and comma's in columns are being split into separate array items.
public List<string> GetData(string dataFile, int row)
{
try
{
var lines = File.ReadAllLines(dataFile).Select(a => a.Split(';'));
var csv = from line in lines select (from piece in line select piece.Split(',')).ToList();
var foo = csv.ToList();
var result = foo[row][0].ToList();
return result;
}
catch
{
return null;
}
}
private const string QUOTE = "\"";
private const string ESCAPED_QUOTE = "\"\"";
private static char[] CHARACTERS_THAT_MUST_BE_QUOTED = { ',', '"', '\n' };
public static string Escape(string s)
{
if (s.Contains(QUOTE))
s = s.Replace(QUOTE, ESCAPED_QUOTE);
if (s.IndexOfAny(CHARACTERS_THAT_MUST_BE_QUOTED) > -1)
s = QUOTE + s + QUOTE;
return s;
}
I am not sure where I can use my escape function in this case.
Example:
Degree,Graduate,08-Dec-17,Level 1,"Advanced, Maths"
The string Advanced, Maths are being split into two different array items which I don't want

You could use regex, linq or just loop through each character and use Booleans to figure out what the current behaviour should be. This question actually got me thinking, as I'd previously just looped through and acted on each character. Here is Linq way of breaking an entire csv document up, assuming the end of line can be found with ';':
private static void Main(string[] args)
{
string example = "\"Hello World, My name is Gumpy!\",20,male;My sister's name is Amy,29,female";
var result1 = example.Split(';')
.Select(s => s.Split('"')) // This will leave anything in abbreviation marks at odd numbers
.Select(sl => sl.Select((ss, index) => index % 2 == 0 ? ss.Split(',') : new string[] { ss })) // if it's an even number split by a comma
.Select(sl => sl.SelectMany(sc => sc));
Console.WriteLine("Press any key to continue.");
Console.ReadKey();
}

Not sure how this performes - but you can solve that with Linq.Aggregate like this:
using System;
using System.Linq;
using System.Collections.Generic;
public class Program
{
public static IEnumerable<string> SplitIt(
char[] splitters,
string text,
StringSplitOptions opt = StringSplitOptions.None)
{
bool inside = false;
var result = text.Aggregate(new List<string>(), (acc, c) =>
{
// this will check each char of your given text
// and accumulate it in the (empty starting) string list
// your splitting chars will lead to a new item put into
// the list if they are not inside. inside starst as false
// and is flipped anytime it hits a "
// at end we either return all that was parsed or only those
// that are neither null nor "" depending on given opt's
if (!acc.Any()) // nothing in yet
{
if (c != '"' && (!splitters.Contains(c) || inside))
acc.Add("" + c);
else if (c == '"')
inside = !inside;
else if (!inside && splitters.Contains(c)) // ",bla"
acc.Add(null);
return acc;
}
if (c != '"' && (!splitters.Contains(c) || inside))
acc[acc.Count - 1] = (acc[acc.Count - 1] ?? "") + c;
else if (c == '"')
inside = !inside;
else if (!inside && splitters.Contains(c)) // ",bla"
acc.Add(null);
return acc;
}
);
if (opt == StringSplitOptions.RemoveEmptyEntries)
return result.Where(r => !string.IsNullOrEmpty(r));
return result;
}
public static void Main()
{
var s = ",,Degree,Graduate,08-Dec-17,Level 1,\"Advanced, Maths\",,";
var spl = SplitIt(new[]{','}, s);
var spl2 = SplitIt(new[]{','}, s, StringSplitOptions.RemoveEmptyEntries);
Console.WriteLine(string.Join("|", spl));
Console.WriteLine(string.Join("|", spl2));
}
}
Output:
|Degree|Graduate|08-Dec-17|Level 1|Advanced, Maths||
Degree|Graduate|08-Dec-17|Level 1|Advanced, Maths

The function gets comma separated fields within a string, excluding commas embedded in a quoted field
The assumptions
It should return empty fields ,,
There are no quotes within a quote field (as per the example)
The method
I uses a for loop with i as a place holder of the current field
It scans for the next comma or quote and if it finds a quote it scans for the next comma to create the field
It needed to be efficient otherwise we would use regex or Linq
The OP didn't want to use a CSV library
Note : There is no error checking, and scanning each character would be faster this was just easy to understand
Code
public List<string> GetFields(string line)
{
var list = new List<string>();
for (var i = 0; i < line.Length; i++)
{
var firstQuote = line.IndexOf('"', i);
var firstComma = line.IndexOf(',', i);
if (firstComma >= 0)
{
// first comma is before the first quote, then its just a standard field
if (firstComma < firstQuote || firstQuote == -1)
{
list.Add(line.Substring(i, firstComma - i));
i = firstComma;
continue;
}
// We have found quote so look for the next comma afterwards
var nextQuote = line.IndexOf('"', firstQuote + 1);
var nextComma = line.IndexOf(',', nextQuote + 1);
// if we found a comma, then we have found the end of this field
if (nextComma >= 0)
{
list.Add(line.Substring(i, nextComma - i));
i = nextComma;
continue;
}
}
list.Add(line.Substring(i)); // if were are here there are no more fields
break;
}
return list;
}
Tests 1
Degree,Graduate,08-Dec-17,Level 1,"Advanced, Maths",another
Degree
Graduate
08-Dec-17
Level 1
"Advanced, Maths"
another
Tests 2
,Degree,Graduate,08-Dec-17,\"asdasd\",Level 1,\"Advanced, Maths\",another
<Empty Line>
Degree
Graduate
08-Dec-17
"asdasd"
Level 1
"Advanced, Maths"
another

validate variable contains string value

I have one variable which contains string value like below:
var stringWithSpecialChar = "/Home%";
Sometimes this variable does not contain any value like below:
var stringWithSpecialChar = "/%";
I have to check here whether this variable contains string value or not.
Everytime string value is changing so it is not sure that i will get the same value another time.

I can't understand what is a valid value in your question, so:
Use below code if a valid value is a value of some letters or some digits:
using System.Linq;
if (str.Any(char.IsLetterOrDigit)
{
//Some codes
}
But I recommend you; for checking a valid or invalid string use Regex like this:
using System.Text.RegularExpressions;
var regex = new Regex(#"[A-Za-z]"); // You have many options here
if (regex.IsMatch(str))
{
//Some codes
}

You can do this, do a foreach loop on your variable to check if it will see a string or letter.
var stringWithSpecialChar = "/Home%";
bool blStringInput;
blStringInput = IsThisString(stringWithSpecialChar);
Method to check if it will see a string value:
public static bool IsThisString(string strInput)
{
foreach (char c in strInput)
{
if (char.IsLetter(c))
return true;
}
return false;
}

Below is a simple implementation of your problem. I have considered that anything in between / and % is a string [It might contain numbers, alphabets or special characters]. Also, I have included a check inside the function whether the string is valid or not by checking whether it starts and ends with / and % respectively.
using System;
class MainClass {
public static void Main (string[] args) {
var stringWithSpecialChar = "/Home%";
bool ans = checkIfStringIsPresent(stringWithSpecialChar);
Console.WriteLine(ans);
stringWithSpecialChar = "/%";
ans = checkIfStringIsPresent(stringWithSpecialChar);
Console.WriteLine(ans);
stringWithSpecialChar = "/hi%";
ans = checkIfStringIsPresent(stringWithSpecialChar);
Console.WriteLine(ans);
stringWithSpecialChar = "/12#%";
ans = checkIfStringIsPresent(stringWithSpecialChar);
Console.WriteLine(ans);
}
public static bool checkIfStringIsPresent(string s){
var len = s.Length;
if(s[0]!='/' || s[len-1]!='%')
return false; // if string doesn't start and and with correct symbols, then return false
var i = 0;
for(i=1;i<len-1;i++){
return true; // something is present in between / and %, so return true
}
return false; // else return false
}
}
Output:
True
False
True
True

If you know the special characters and know they are at the begining and end of the string, Trim() could be used:
var stringWithSpecialChar = "/Home%";
var value = stringWithSpecialChar.Trim('/', '%');
if(!string.IsNullOrEmpty(value))
// Use value...
One could also use string.IsNullOrWhiteSpace(value) in the condition depending on your needs.

c# contains word exception number

I need to search a string and see if it contains "<addnum(x)>"
I have used .contains on the other words that i searched for and the easiest way i could think for is you somehow could make exception for numbers or do you need to use another code for that?
My code this far.
public List<string> arguments = new List<string>();
public void Custom_naming(string name_code)
{
arguments.Add("Changing the name to " + name_code); // Sets the new name.
if( name_code.Contains("<addnum>") )
{
Add_number();
}
if (name_code.Contains("<addnum(x)>"))
{// X = any number.
}
}
private void Add_number()
{
arguments.Add("Replaces all <addnum> with a number");
}
private void Add_number(int zeros)
{
arguments.Add("Replaces all <addnumxx> with a number with lentgh of");
}

You probably need to use a regular expression:
var match = Regex.Match(name_code, #"<addnum(?:\((\d+)\))?>");
if (match.Success)
{
int zeros;
if (int.TryParse(match.Groups[1].Value, out zeros))
{
Add_number(zeros);
}
else
{
Add_number();
}
}
This will return invoke the appropriate Add_number method if name_code contains <addnum> or anything like <addnum(123)>.
If there could possibly be more than one such in name_code, e.g. <addnum(1)><addnum(2)>, you'll want to use a loop to analyze each match, like this:
var matches = Regex.Matches(name_code, #"<addnum(?:\((\d+)\))?>");
foreach(var match in matches)
{
int zeros;
if (int.TryParse(match.Groups[1].Value, out zeros))
{
Add_number(zeros);
}
else
{
Add_number();
}
}

Use regular expression:
string s = "Foo <addnum(8)> bar.";
var contains = Regex.IsMatch(s, #"<addnum\(\d+\)>");
If you want also extract number:
string s = "Foo <addnum(42)> bar.";
var match = Regex.Match(s, #"<addnum\((\d+)\)>");
if (match.Success)
{
// assume you have valid integer number
var number = Int32.Parse(match.Groups[1].Value);
}

How can I search through a string in C# and replace areas bounded by a pattern?

We tried a few solutions now that try and use XML parsers. All fail because the strings are not always 100% valid XML. Here's our problem.
We have strings that look like this:
var a = "this is a testxxx of my data yxxx and of these xxx parts yxxx";
var b = "hello testxxx world yxxx ";
"this is a testxxx3yxxx and of these xxx1yxxx";
"hello testxxx1yxxx ";
The key here is that we want to do something to the data between xxx and yxxx. In the example above I would need a function that counts words and replaces the strings with a word count.
Is there a way we can process the string a and apply a function to change the data that's between the xxx and yxxx? Any function right now as we're just trying to get an idea of how to code this.

You can use Split method:
var parts = a.Split(new[] {"xxx", "yxxx"}, StringSplitOptions.None)
.Select((s, index) =>
{
string s1 = index%2 == 1 ? string.Format("{0}{2}{1}", "xxx", "yxxx", s + "1") : s;
return s1;
});
var result = string.Join("", parts);

If it always going to xxx and yxxx, you can use regex as suggested.
var stringBuilder = new StringBuilder();
Regex regex = new Regex("xxx(.*?)yxxx");
var splitGroups = Regex.Match(a);
foreach(var group in splitGroups)
{
var value = splitGroupsCopy[i];
// do something to value and then append it to string builder
stringBuilder.Append(string.Format("{0}{1}{2}", "xxx", value, "yxxx"));
}
I suppose this is as basic as it gets.

Using Regex.Replace will replace all the matches with your choice of text, something like this:
Regex rgx = new Regex("xxx.+yxxx");
string cleaned = rgx.Replace(a, "replacementtext");

This code will process each of the parts delimited by "xxx". It preserves the "xxx" separators. If you do not want to preserve the "xxx" separators, remove the two lines that say "result.Append(separator);".
Given:
"this is a testxxx of my data yxxx and there are many of these xxx parts yxxx"
It prints:
"this is a testxxx>> of my data y<<xxx and there are many of these xxx>> parts y<<xxx"
I'm assuming that's the kind of thing you want. Add your own processing to "processPart()".
using System;
using System.Text;
namespace ConsoleApplication1
{
internal class Program
{
private static void Main(string[] args)
{
string text = "this is a testxxx of my data yxxx and there are many of these xxx parts yxxx";
string separator = "xxx";
var result = new StringBuilder();
int index = 0;
while (true)
{
int start = text.IndexOf(separator, index);
if (start < 0)
{
result.Append(text.Substring(index));
break;
}
result.Append(text.Substring(index, start - index));
int end = text.IndexOf(separator, start + separator.Length);
if (end < 0)
{
throw new InvalidOperationException("Unbalanced separators.");
}
start += separator.Length;
result.Append(separator);
result.Append(processPart(text.Substring(start, end-start)));
result.Append(separator);
index = end + separator.Length;
}
Console.WriteLine(result);
}
private static string processPart(string part)
{
return ">>" + part + "<<";
}
}
}
[EDIT] Here's the code amended to work with two different separators:
using System;
using System.Text;
namespace ConsoleApplication1
{
internal class Program
{
private static void Main(string[] args)
{
string text = "this is a test<pre> of my data y</pre> and there are many of these <pre> parts y</pre>";
string separator1 = "<pre>";
string separator2 = "</pre>";
var result = new StringBuilder();
int index = 0;
while (true)
{
int start = text.IndexOf(separator1, index);
if (start < 0)
{
result.Append(text.Substring(index));
break;
}
result.Append(text.Substring(index, start - index));
int end = text.IndexOf(separator2, start + separator1.Length);
if (end < 0)
{
throw new InvalidOperationException("Unbalanced separators.");
}
start += separator1.Length;
result.Append(separator1);
result.Append(processPart(text.Substring(start, end-start)));
result.Append(separator2);
index = end + separator2.Length;
}
Console.WriteLine(result);
}
private static string processPart(string part)
{
return "|" + part + "|";
}
}
}

The indexOf() function will return to you the index of the first occurrence of a given substring.
(My indices might be a bit off, but) I would suggest doing something like this:
var searchme = "this is a testxxx of my data yxxx and there are many of these xxx parts yxxx";
var startindex= searchme.indexOf("xxx");
var endindex = searchme.indexOf("yxxx") + 3; //added 3 to find the index of the last 'x' instead of the index of the 'y' character
var stringpiece = searchme.substring(startindex, endindex - startindex);
and you can repeat that while startindex != -1
Like I said, the indices might be slightly off, you might have to add a +1 or -1 somewhere, but this will get you along nicely (I think).
Here is a little sample program that counts chars instead of words. But you should just need to change the processor function.
var a = "this is a testxxx of my data yxxx and there are many of these xxx parts yxxx";
a = ProcessString(a, CountChars);
string CountChars(string a)
{
return a.Length.ToString();
}
string ProcessString(string a, Func<string, string> processor)
{
int idx_start, idx_end = -4;
while ((idx_start = a.IndexOf("xxx", idx_end + 4)) >= 0)
{
idx_end = a.IndexOf("yxxx", idx_start + 3);
if (idx_end < 0)
break;
var string_in_between = a.Substring(idx_start + 3, idx_end - idx_start - 3);
var newString = processor(string_in_between);
a = a.Substring(0, idx_start + 3) + newString + a.Substring(idx_end, a.Length - idx_end);
idx_end -= string_in_between.Length - newString.Length;
}
return a;
}

I would use Regex Groups:
Here my solution to get the parts in the string:
private static IEnumerable<string> GetParts( string searchFor, string begin, string end ) {
string exp = string.Format("({0}(?<searchedPart>.+?){1})+", begin, end);
Regex regex = new Regex(exp);
MatchCollection matchCollection = regex.Matches(searchFor);
foreach (Match match in matchCollection) {
Group #group = match.Groups["searchedPart"];
yield return #group.ToString();
}
}
you can use it like to get the parts:
string a = "this is a testxxx of my data yxxx and there are many of these xxx parts yxxx";
IEnumerable<string> parts = GetParts(a, "xxx", "yxxx");
To replace the parts in the original String you can use the Regex Group to determine Length and StartPosition (#group.Index, #group.Length).