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How can I add a space between every 3 characters counting from the right to the left in a string in C#?

I want to add space between every 3 characters in a string in C#, but count from right to left.
For example :
11222333 -> 11 222 333

Answer by #Jimi from comments (will delete if they post their own)
var YourString = "11222333";
var sb = new StringBuilder(YourString);
for (int i = sb.Length -3; i >= 0; i -= 3)
sb.Insert(i, ' ');
return sb.ToString();
The benefit of this algorithm appears to be that you are working backwards through the string and therefore only moving a certain amount on each run, rather than the whole string.

If you are trying to format a string as a number according to some locale conventions you can use the NumberFormat class to set how you want a number to be formatted as a string
So for example
string input = "11222333";
NumberFormatInfo currentFormat = new NumberFormatInfo();
currentFormat.NumberGroupSeparator = " ";
if(Int32.TryParse(input, NumberStyles.None, currentFormat, out int result))
{
string output = result.ToString("N0", currentFormat);
Console.WriteLine(output); // 11 222 333
}

The following recursive function would do the job:
string space3(string s)
{
int len3 = s.Length - 3;
return (len <= 0) ? s
: (space3(s.Substring(0, len3)) + " " + s.Substring(len3));
}
C# 8.0 introduced string ranges. Ranges allow for a more compact form:
string space3(string s)
{
return (s.Length <= 3) ? s
: (space3(s[..^3]) + " " + s[^3..]);
}

Using Regex.Replace:
string input = "11222333";
string result = Regex.Replace( input, #"\d{3}", #" $0", RegexOptions.RightToLeft );
Demo and detailed explanation of RegEx pattern at regex101.
tl;dr: Match groups of 3 digits from right to left and replace them by space + the 3 digits.

The most efficient algorithm I can come up with is the following:
var sb = new StringBuilder(YourString.Length + YourString.Length / 3 + 1);
if (YourString.Length % 3 > 0)
{
sb.Append(YourString, 0, YourString.Length % 3);
sb.Append(' ');
}
for (var i = YourString.Length % 3; i < YourString.Length; i += 3)
{
sb.Append(YourString, i, 3);
sb.Append(' ');
}
return sb.ToString();
We first assign a StringBuilder of the correct size.
Then we check to see if we need to append the first one or two characters. Then we loop the rest.
dotnetfiddle

string.PadRight() doesn't seem to work in my code

I have a Powershell output to re-format, because formatting gets lost in my StandardOutput.ReadToEnd().There are several blanks to be removed in a line and I want to get the output formatted readable.
Current output in my messageBox looks like
Microsoft.MicrosoftJigsaw All
Microsoft.MicrosoftMahjong All
What I want is
Microsoft.MicrosoftJigsaw All
Microsoft.MicrosoftMahjong All
What am I doing wrong?
My C# knowledge still is basic level only
I found this question here, but maybe I don't understand the answer correctly. The solution doesn't work for me.
Padding a string using PadRight method
This is my current code:
string first = "";
string last = "";
int idx = line.LastIndexOf(" ");
if (idx != -1)
{
first = line.Substring(0, idx).Replace(" ","").PadRight(10, '~');
last = line.Substring(idx + 1);
}
MessageBox.Show(first + last);

String.PadLeft() first parameter defines the length of the padded string, not padding symbol count.
Firstly, you can iterate through all you string, split and save.
Secondly, you should get the longest string length.
Finally, you can format strings to needed format.
var strings = new []
{
"Microsoft.MicrosoftJigsaw All",
"Microsoft.MicrosoftMahjong All"
};
var keyValuePairs = new List<KeyValuePair<string, string>>();
foreach(var item in strings)
{
var parts = item.Split(new [] {" "}, StringSplitOptions.RemoveEmptyEntries);
keyValuePairs.Add(new KeyValuePair<string, string>(parts[0], parts[1]));
}
var longestStringCharCount = keyValuePairs.Select(kv => kv.Key).Max(k => k.Length);
var minSpaceCount = 5; // min space count between parts of the string
var formattedStrings = keyValuePairs.Select(kv => string.Concat(kv.Key.PadRight(longestStringCharCount + minSpaceCount, ' '), kv.Value));
foreach(var item in formattedStrings)
{
Console.WriteLine(item);
}
Result:
Microsoft.MicrosoftJigsaw All
Microsoft.MicrosoftMahjong All

The PadRight(10 is not enough, it is the size of the complete string.
I would probably go for something like:
string[] lines = new[]
{
"Microsoft.MicrosoftJigsaw All",
"Microsoft.MicrosoftMahjong All"
};
// iterate all (example) lines
foreach (var line in lines)
{
// split the string on spaces and remove empty ones
// (so multiple spaces are ignored)
// ofcourse, you must check if the splitted array has atleast 2 elements.
string[] splitted = line.Split(new Char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
// reformat the string, with padding the first string to a total of 40 chars.
var formatted = splitted[0].PadRight(40, ' ') + splitted[1];
// write to anything as output.
Trace.WriteLine(formatted);
}
Will show:
Microsoft.MicrosoftJigsaw All
Microsoft.MicrosoftMahjong All
So you need to determine the maximum length of the first string.

Assuming the length of second part of your string is 10 but you can change it. Try below piece of code:
Function:
private string PrepareStringAfterPadding(string line, int totalLength)
{
int secondPartLength = 10;
int lastIndexOfSpace = line.LastIndexOf(" ");
string firstPart = line.Substring(0, lastIndexOfSpace + 1).Trim().PadRight(totalLength - secondPartLength);
string secondPart = line.Substring(lastIndexOfSpace + 1).Trim().PadLeft(secondPartLength);
return firstPart + secondPart;
}
Calling:
string line1String = PrepareStringAfterPadding("Microsoft.MicrosoftJigsaw All", 40);
string line2String = PrepareStringAfterPadding("Microsoft.MicrosoftMahjong All", 40);
Result:
Microsoft.MicrosoftJigsaw All
Microsoft.MicrosoftMahjong All
Note:
Code is given for demo purpose please customize the totalLength and secondPartLength and calling of the function as per your requirement.

C# fix sentence

I need to take a sentence in that is all on one line with no spaces and each new word has a captial letter EX. "StopAndSmellTheRoses" and then convert it to "Stop and smell the roses" This is my function that I have but I keep getting an argument out of range error on the insert method. Thanks for any help in advance.
private void FixSentence()
{
// String to hold our sentence in trim at same time
string sentence = txtSentence.Text.Trim();
// loop through the string
for (int i = 0; i < sentence.Length; i++)
{
if (char.IsUpper(sentence, i) & sentence[i] != 0)
{
// Change to lowercase
char.ToLower(sentence[i]);
// Insert space behind the character
// This is where I get my error
sentence = sentence.Insert(i-1, " ");
}
}
// Show our Fixed Sentence
lblFixed.Text = "";
lblFixed.Text = "Fixed: " + sentence;
}

The best way to build up a String in this manner is to use a StringBuilder instance.
var sentence = txtSentence.Text.Trim();
var builder = new StringBuilder();
foreach (var cur in sentence) {
if (Char.IsUpper(cur) && builder.Length != 0) {
builder.Append(' ');
}
builder.Append(cur);
}
// Show our Fixed Sentence
lblFixed.Text = "";
lblFixed.Text = "Fixed: " + builder.ToString();
Using the Insert method creates a new string instance every time resulting in a lot of needlessly allocated values. The StringBuilder though won't actually allocate a String until you call the ToString method.

You can't modify the sentence variable in the loop that is going through it.
Instead, you need to have a second string variable that you append all of the found words.

Here is the answer
var finalstr = Regex.Replace(
"StopAndSmellTheRoses",
"(?<=[a-z])(?<x>[A-Z])|(?<=.)(?<x>[A-Z])(?=[a-z])|(?<=[^0-9])(?<x>[0-9])(?=.)",
me => " " + me.Value.ToLower()
);
will output
Stop and smell the roses

Another version:
public static class StringExtensions
{
public static string FixSentence(this string instance)
{
char[] capitals = Enumerable.Range(65, 26).Select(x => (char)x).ToArray();
string[] words = instance.Split(capitals);
string result = string.Join(' ', words);
return char.ToUpper(result[0]) + result.Substring(1).ToLower();
}
}

How to insert spaces between the characters of a string

Is there an easy method to insert spaces between the characters of a string? I'm using the below code which takes a string (for example ( UI$.EmployeeHours * UI.DailySalary ) / ( Month ) ) . As this information is getting from an excel sheet, i need to insert [] for each columnname. The issue occurs if user avoids giving spaces after each paranthesis as well as an operator. AnyOne to help?
text = e.Expression.Split(Splitter);
string expressionString = null;
for (int temp = 0; temp < text.Length; temp++)
{
string str = null;
str = text[temp];
if (str.Length != 1 && str != "")
{
expressionString = expressionString + "[" + text[temp].TrimEnd() + "]";
}
else
expressionString = expressionString + str;
}
User might be inputing something like (UI$.SlNo-UI+UI$.Task)-(UI$.Responsible_Person*UI$.StartDate) while my desired output is ( [UI$.SlNo-UI] + [UI$.Task] ) - ([UI$.Responsible_Person] * [UI$.StartDate] )

Here is a short way to insert spaces after every single character in a string (which I know isn't exactly what you were asking for):
var withSpaces = withoutSpaces.Aggregate(string.Empty, (c, i) => c + i + ' ');
This generates a string the same as the first, except with a space after each character (including the last character).

You can do that with regular expressions:
using System.Text.RegularExpressions;
class Program {
static void Main() {
string expression = "(UI$.SlNo-UI+UI$.Task)-(UI$.Responsible_Person*UI$.StartDate) ";
string replaced = Regex.Replace(expression, #"([\w\$\.]+)", " [ $1 ] ");
}
}
If you are not familiar with regular expressions this might look rather cryptic, but they are a powerful tool, and worth learning. In case, you may check how regular expressions work, and use a tool like Expresso to test your regular expressions.
Hope this helps...

Here is an algorithm that does not use regular expressions.
//Applies dobule spacing between characters
public static string DoubleSpace(string s)
{
if (string.IsNullOrEmpty(s))
{
return string.Empty;
}
char[] a = s.ToCharArray();
char[] b = new char[ (a.Length * 2) - 1];
int bIndex = 0;
for(int i = 0; i < a.Length; i++)
{
b[bIndex++] = a[i];
//Insert a white space after the char
if(i < (a.Length - 1))
{
b[bIndex++] = ' ';
}
}
return new string(b);
}

Well, you can do this by using Regular expressions, search for specific paterns and add brackets where needed. You could also simply Replace every Paranthesis with the same Paranthesis but with spaces on each end.
I would also advice you to use StringBuilder aswell instead of appending to an existing string (this creates a new string for each manipulation, StringBuilder has a smaller memory footprint when doing this kind of manipulation)

How can I create a string in C# programmatically?

I have a string, and I want to add a number of spaces to the beginning of that string based on an int variable.
I want to do something like this:
int NumberOfTabs = 2;
string line = "my line";
string line = String.Format("{0}{1}", " " * NumberOfTabs, line);
...and now line would have 8 spaces
What is the easiest way to do this?

You can use the String(char, Int32) constructor like this:
string line = String.Format("{0}{1}", new String(' ', NumberofTabs * 4), line);
or a bit more efficient:
string line = String.Concat(new String(' ', NumberofTabs * 4), line);
or, a bit more concise :)
string line = new String(' ', NumberofTabs * 4).Concat(line);
A comment made a good point, if you want to actually have the tab character, just change the ' ' to '\t' and take out the * 4 like this:
string line = String.Concat(new String('\t', NumberofTabs), line);

int i=8;
System.Text.StringBuilder sb = new System.Text.StringBuilder();
sb.Append(" ", i);

new string(' ', NumberOfTabs )

str = str.PadLeft(str.Length+tabs*4);

In C# strings are immutable. You should really use the stringbuilder class.
Code examples are listed in the link:
http://msdn.microsoft.com/en-us/library/system.text.stringbuilder.aspx

You could use something like this:
String.Empty.PadRight(NumberOfTabs)

You can add tabs at the beginning of your text like this:
line.PadLeft(NumberOfTabs, '\t');
\t being the escape character for "tab"
(Inserting a tab character into text using C#)

int NumberOfTabs = 2;
string line = "my line";
string results = line.PadLeft(line.Length + NumberOfTabs, ' ');

Not the best answer by any measure, but here's an amusing one, a little LINQ one-liner:
var result = new string(Enumerable.Repeat(' ', count).Concat("my line").ToArray());

You can create a new string containing a custom number of spaces. Unfortunately, there's no string multiplication like in Python (" " * 2). But you can multiply the number of spaces by 4 to get "tabs":
int numberOfTabs = 2;
string line = "my line";
string whitespaces = new string(' ', numberOfTabs * 4);
string s = whitespaces + line;