We Keep Coding

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.

Need to split something dynamically from a string

I have a string which is somewhat like this:
string data = "I have a {apple} and a {orange}";
I need to extract the content inside {}, let's say for 10 times
I tried this
string[] split = data.Split(new char[] { '{', '}' }, StringSplitOptions.RemoveEmptyEntries);
The problem is my data is going to be dynamic and I wouldn't know at what instance the {<>} would be present, it can also be something like this
Give {Pen} {Pencil}
I guess the above method wouldn't work, so I would really like to know a dynamic way to do this. Any input would be really helpful.
Thanks and Regards

Try this:
string data = "I have a {apple} and a {orange}";
Regex rx = new Regex("{(.*?)}");
foreach (Match item in rx.Matches(data))
{
Console.WriteLine(item.Groups[1].Value);
}
You need to use Regex to get all values you need.

If the string between {} does not contain nested {} you can use a regex to perform this task:
string data = "I have a {apple} and a {orange}";
Regex reg = new Regex(#"\{(?<Name>[A-z0-9]*)\}");
var matches = reg.Matches(data);
foreach (var m in matches.OfType<Match>())
{
Console.WriteLine($"Found {m.Groups["Name"].Value} at {m.Index}");
}
To replace the strings between {} you can use Regex.Replace:
reg.Replace(data, m => m.Groups["Name"].Value + "_")
// Will produce "I have a apple_ and a orange_"
To get the rest of the string, you can use Regex.Split:
Regex reg2 = new Regex(#"\{[A-z0-9]*\}");
var result = reg2.Split(data);
// will contain "I have a ", " and a ", "", you might want to remove ""

As I understand, you want to split that string into parts like this:
I have a
{apple}
and a
{orange}
And then you want to go over those parts and do something with them, and that something is different depending on whether part is enclosed in {} or not. If so - you need Regex.Split:
string data = "I have a {apple} and a {orange}";
var parts = Regex.Split(data, #"({.*?})");
foreach (var part in parts) {
if (part.StartsWith("{") && part.EndsWith("}")) {
var trimmed = part.TrimStart('{').TrimEnd('}');
// "apple" and "orange" go here
// do something with {} part
}
else {
// "I have a " and " and a " go here
// do something with other part
}
}

Parsing string with 3 hyphens C#

I have string COO70-123456789-12345-1. I need to parse based on the "-" not the length of the substrings and use the parsed values. I have tried using Regular expressions but having issues.Please suggest.
Also after I have split the values I need to use each values: string A = COO70, int B = 123456789, int C = 12345, short D = 1 . How do I get it in different variables A,B,C,D.
string[] results = UniqueId.Split('-');
string A = results[0];
string B = results[1];
string C = results[2];
int k_id = Convert.ToInt32(k_id);
string D = results[3];
short seq = Convert.ToInt16(seq);

string s = "COO70-123456789-12345-1";
string[] split = s.Split('-'); //=> {"COO70", "123456789", "12345", "1"}

Use indexOf
To find everything before the first hyphen use:
string original= "COO70-123456789-12345-1";
string toFirstHyphen=original.Substring(0,original.IndexOf("-"));
Or if you want every section use split like the above example.

You can verify whether the input is formatted as you want and then split to get the parts.
using System;
using System.Text.RegularExpressions;
class Program
{
static void Main()
{
string pattern = #"(?x)^(\w+-\w+-\w+-\w+)$";
Regex reg = new Regex(pattern);
string test = "word-6798-3401-001";
if((reg.Match(test).Success))
foreach (var x in test.Split(new char[] {'-'}))
Console.WriteLine(x);
}
}

So it sounds like you first want to split it, but then store it into your values.
I would do something like this:
var myString = "COO70-123456789-12345-1";
var stringSet = myString.Split("-"); // This returns an array of values.
Now we need to verify that we receive only 4 sub strings:
if (stringSet.Count != 4)
throw Exception e; // Throw a real exception, not this
From here we need to know what order our strings should be in and assign them:
var A = stringSet[0];
var B = stringSet[1];
var C = stringSet[2];
var D = stringSet[3];
While this should answer your question as posed, I would recommend you work with stringSet differently personally.

Parse multiple values from string c#

Suppose I have written "5 and 6" or "5+6". How can I assign 5 and 6 to two different variables in c# ?
P.S. I also want to do certain work if certain chars are found in string. Suppose I have written 5+5. Will this code do that ?
if(string.Contains("+"))
{
sum=x+y;
}

string input="5+5";
var numbers = Regex.Matches(input, #"\d+")
.Cast<Match>()
.Select(m => m.Value)
.ToList();

Personally, I would vote against doing some splitting and regular expression stuff.
Instead I would (and did in the past) use one of the many Expression Evaluation libraries, like e.g. this one over at Code Project (and the updated version over at CodePlex).
Using the parser/tool above, you could do things like:
A simple expression evaluation then could look like:
Expression e = new Expression("5 + 6");
Debug.Assert(11 == e.Evaluate());
To me this is much more error-proof than doing the parsing all by myself, including regular expressions and the like.

You should use another name for your string than string
var numbers = yourString.Split("+");
var sum = Convert.ToInt32(numbers[0]) + Convert.ToInt32(numbers[1]);
Note: Thats an implementation without any error checking or error handling...

If you want to assign numbers from string to variables, you will have to parse string and make conversion.
Simple example, if you have text with only one number
string text = "500";
int num = int.Parse(text);
Now, if you want to parse something more complicated, you can use split() and/or regex to get all numbers and operators between them. Than you just iterate array and assign numbers to variables.
string text = "500+400";
if (text.Contains("+"))
{
String[] data = text.Split("+");
int a = int.Parse(data[0]);
int b = int.Parse(data[1]);
int res = a + b;
}
Basicly, if you have just 2 numbers and operazor between them, its ok. If you want to make "calculator" you will need something more, like Binary Trees or Stack.

Use the String.Split method. It splits your string rom the given character and returns a string array containing the value that is broken down into multiple pieces depending on the character to break, in this case, its "+".
int x = 0;
int y = 0;
int z = 0;
string value = "5+6";
if (value.Contains("+"))
{
string[] returnedArray = value.Split('+');
x = Convert.ToInt32(returnedArray[0]);
y = Convert.ToInt32(returnedArray[1]);
z = x + y;
}

Something like this may helpful
string strMy = "5&6";
char[] arr = strMy.ToCharArray();
List<int> list = new List<int>();
foreach (char item in arr)
{
int value;
if (int.TryParse(item.ToString(), out value))
{
list.Add(item);
}
}
list will contains all the integer values

You can use String.Split method like;
string s = "5 and 6";
string[] a = s.Split(new string[] { "and", "+" }, StringSplitOptions.RemoveEmptyEntries);
Console.WriteLine(a[0].Trim());
Console.WriteLine(a[1].Trim());
Here is a DEMO.

Use regex to get those value and then switch on the operand to do the calculation
string str = "51 + 6";
str = str.Replace(" ", "");
Regex regex = new Regex(#"(?<rightHand>\d+)(?<operand>\+|and)(?<leftHand>\d+)");
var match = regex.Match(str);
int rightHand = int.Parse(match.Groups["rightHand"].Value);
int leftHand = int.Parse(match.Groups["leftHand"].Value);
string op = match.Groups["operand"].Value;
switch (op)
{
case "+":
.
.
.
}

Split function maybe is comfortable in use but it is space inefficient
because it needs array of strings
Maybe Trim(), IndexOf(), Substring() can replace Split() function

Count regex replaces (C#)

Is there a way to count the number of replacements a Regex.Replace call makes?
E.g. for Regex.Replace("aaa", "a", "b"); I want to get the number 3 out (result is "bbb"); for Regex.Replace("aaa", "(?<test>aa?)", "${test}b"); I want to get the number 2 out (result is "aabab").
Ways I can think to do this:
Use a MatchEvaluator that increments a captured variable, doing the replacement manually
Get a MatchCollection and iterate it, doing the replacement manually and keeping a count
Search first and get a MatchCollection, get the count from that, then do a separate replace
Methods 1 and 2 require manual parsing of $ replacements, method 3 requires regex matching the string twice. Is there a better way.

Thanks to both Chevex and Guffa. I started looking for a better way to get the results and found that there is a Result method on the Match class that does the substitution. That's the missing piece of the jigsaw. Example code below:
using System.Text.RegularExpressions;
namespace regexrep
{
class Program
{
static int Main(string[] args)
{
string fileText = System.IO.File.ReadAllText(args[0]);
int matchCount = 0;
string newText = Regex.Replace(fileText, args[1],
(match) =>
{
matchCount++;
return match.Result(args[2]);
});
System.IO.File.WriteAllText(args[0], newText);
return matchCount;
}
}
}
With a file test.txt containing aaa, the command line regexrep test.txt "(?<test>aa?)" ${test}b will set %errorlevel% to 2 and change the text to aabab.

You can use a MatchEvaluator that runs for each replacement, that way you can count how many times it occurs:
int cnt = 0;
string result = Regex.Replace("aaa", "a", m => {
cnt++;
return "b";
});
The second case is trickier as you have to produce the same result as the replacement pattern would:
int cnt = 0;
string result = Regex.Replace("aaa", "(?<test>aa?)", m => {
cnt++;
return m.Groups["test"] + "b";
});

This should do it.
int count = 0;
string text = Regex.Replace(text,
#"(((http|ftp|https):\/\/|www\.)[\w\-_]+(\.[\w\-_]+)+([\w\-\.,#?^=%&:/~\+#]*[\w\-\#?^=%&/~\+#])?)", //Example expression. This one captures URLs.
match =>
{
string replacementValue = String.Format("<a href='{0}'>{0}</a>", match.Value);
count++;
return replacementValue;
});
I am not on my dev computer so I can't do it right now, but I am going to experiment later and see if there is a way to do this with lambda expressions instead of declaring the method IncrementCount() just to increment an int.
EDIT modified to use a lambda expression instead of declaring another method.
EDIT2 If you don't know the pattern in advance, you can still get all the groupings (The $ groups you refer to) within the match object as they are included as a GroupCollection. Like so:
int count = 0;
string text = Regex.Replace(text,
#"(((http|ftp|https):\/\/|www\.)[\w\-_]+(\.[\w\-_]+)+([\w\-\.,#?^=%&:/~\+#]*[\w\-\#?^=%&/~\+#])?)", //Example expression. This one captures URLs.
match =>
{
string replacementValue = String.Format("<a href='{0}'>{0}</a>", match.Value);
count++;
foreach (Group g in match.Groups)
{
g.Value; //Do stuff with g.Value
}
return replacementValue;
});