Develop Reference

Editing string in C#

given a string with words separated by spaces how would you go about merging two words if one of them is made by one character only ? An example should clarify:
"a bcd tttt" => "abcd tttt"
"abc d hhhh" => "abcd hhhh"
I would like to merge the single characer word with the one on the left in all cases where it is not the first word in the string, in this case i would like to merge it with the one on the right.
I am trying to loop through the string and create some logic but it turned out to be more complex than i was expecting.

Try the below program's approach:
using System;
using System.Text;
public class Program
{
public static void Main()
{
var delimiter=new char[]{' '};
var stringToMerge="abc d hhhh";
var splitArray=stringToMerge.Split(delimiter);
var stringBuilder=new StringBuilder();
for(int wordIndex=0;wordIndex<splitArray.Length;wordIndex++)
{
var word=splitArray[wordIndex];
if(wordIndex!=0 && word.Length>1)
{
stringBuilder.Append(" ");
}
stringBuilder.Append(word);
}
Console.WriteLine(stringBuilder.ToString());
}
}
Basically, you split the string to words, then using StringBuilder, build a new string, inserting a space before a word only if the word is larger than one character.

One way to approach this is to first use string.Split(' ') to get an array of words, which is easier to deal with.
Then you can loop though the words, handling single character words by concatenating them with the previous word, with special handling for the first word.
One such approach:
public static void Main()
{
string data = "abcd hhhh";
var words = data.Split(' ');
var sb = new StringBuilder();
for (int i = 0; i < words.Length; ++i)
{
var word = words[i];
if (word.Length == 1)
{
sb.Append(word);
if (i == 0 && i < words.Length - 1) // Single character first word is special case: Merge with next word.
sb.Append(words[++i]); // Note the "++i" to increment the loop counter, skipping the next word.
}
else
{
sb.Append(' ' + word);
}
}
var result = sb.ToString();
Console.WriteLine(result);
}
Note that this will concatenate multiple instances of single-letter words, so that "a b c d e" will result in "abcde" and "ab c d e fg" will result in "abcde fg". You don't actually specify what should happen in this case.

if you want to do it with a plain for loop and string walking:
using System;
using System.Text;
public class Program
{
public static void Main()
{
Console.WriteLine(MergeOrphant("bcd a tttt") == "bcda tttt");
Console.WriteLine(MergeOrphant("bcd a tttt a") == "bcda tttta");
Console.WriteLine(MergeOrphant("a bcd tttt") == "abcd tttt");
Console.WriteLine(MergeOrphant("a b") == "ab");
}
private static string MergeOrphant(string source)
{
var stringBuilder = new StringBuilder();
for (var i = 0; i < source.Length; i++)
{
if (i == 1 && char.IsWhiteSpace(source[i]) && char.IsLetter(source[i - 1])) {
i++;
}
if (i > 0 && char.IsWhiteSpace(source[i]) && char.IsLetter(source[i - 1]) && char.IsLetter(source[i + 1]) && (i + 2 == source.Length || char.IsWhiteSpace(source[i + 2])) )
{
i++;
}
stringBuilder.Append(source[i]);
}
return stringBuilder.ToString();
}
}

Quite short with Regex.
string foo = "a bcd b tttt";
foo = Regex.Replace(foo, #"^(\w) (\w{2,})", "$1$2");
foo = Regex.Replace(foo, #"(\w{2,}) (\w)\b", "$1$2");
Be aware \w is [a-zA-Z0-9_] if you need an other definition you have to define you own character class.

My answer would not be the best practice but it works for your second case, but still you should be clear about the letter merging rules.
public static void Main()
{
Console.WriteLine(Edit("abc d hhhh") == "abcd hhhh");
Console.WriteLine(Edit("abc d hhhh a") == "abcd hhhha");
Console.WriteLine(Edit("abc d hhhh a b") == "abcd hhhhab");
Console.WriteLine(Edit("abc d hhhh a def g") == "abcd hhhha defg");
}
public static string Edit(string str)
{
var result = string.Empty;
var split = str.Split(' ', StringSplitOptions.RemoveEmptyEntries);
for (int i = 0; i < split.Length; i++)
{
if(i == 0)
result += split[i];
else
{
if (i > 0 && split[i].Length == 1)
{
result += split[i];
}
else
{
result += $" {split[i]}";
}
}
}
return result;
}
As I have mentioned above, this does not work for your 1st case which is : Edit("a bcd") would not generate "abcd".

Expanding on Matthew's answer,
If you don't want the extra space in the output you can change the last line to;
Console.WriteLine(result.TrimStart(' '));

Split string and keeping the delimiter without Regex C#

Problem: spending too much time solving simple problems. Oh, here's the simple problem.
Input: string inStr, char delimiter
Output: string[] outStrs where string.Join("", outStrs) == inStr and each item in outStrs before the last item must end with the delimiter. If inStr ends with the delimiter, then the last item in outStrs ends with the delimiter as well.
Example 1:
Input: "my,string,separated,by,commas", ','
Output: ["my,", "string,", "separated,", "by,", "commas"]
Example 2:
Input: "my,string,separated,by,commas,", ','
Output: ["my,", "string,", "separated,", "by,", "commas,"] (notice trailing comma)
Solution with Regex: here
I want to avoid using Regex, simply because this requires only character comparison. It's algorithmically just as complex to do as what string.Split() does. It bothers me that I cannot find a more succinct way to do what I want.
My bad solution, which doesn't work for me... it should be faster and more succinct.
var outStr = inStr.Split(new[]{delimiter},
StringSplitOptions.RemoveEmptyEntries)
.Select(x => x + delimiter).ToArray();
if (inStr.Last() != delimiter) {
var lastOutStr = outStr.Last();
outStr[outStr.Length-1] = lastOutStr.Substring(0, lastOutStr.Length-1);
}

Using LINQ:
string input = "my,string,separated,by,commas";
string[] groups = input.Split(',');
string[] output = groups
.Select((x, idx) => x + (idx < groups.Length - 1 ? "," : string.Empty))
.Where(x => x != "")
.ToArray();
Split the string into groups, then transform every group that is not the last element by appending a comma to it.
Just thought of another way you could do it, but I don't think this method is as clear:
string[] output = (input + ',').Split( new[] { "," }, StringSplitOptions.RemoveEmptyEntries)
.Select(x => x + ',').ToArray();

Seems pretty simple to me without using Regex:
string inStr = "dasdasdas";
char delimiter = 'A';
string[] result = inStr.Split(new string[] { inStr }, System.StringSplitOptions.RemoveEmptyEntries);
string lastItem = result[result.Length - 1];
int amountOfLoops = lastItem[lastItem.Length - 1] == delimiter ? result.Length - 1 : result.Length - 2;
for (int i = 0; i < amountOfLoops; i++)
{
result[i] += delimiter;
}

public static IEnumerable<string> SplitAndKeep(this string s, string[] delims)
{
int start = 0, index;
string selectedSeperator = null;
while ((index = s.IndexOfAny(delims, start, out selectedSeperator)) != -1)
{
if (selectedSeperator == null)
continue;
if (index - start > 0)
yield return s.Substring(start, index - start);
yield return s.Substring(index, selectedSeperator.Length);
start = index + selectedSeperator.Length;
}
if (start < s.Length)
{
yield return s.Substring(start);
}
}

Best way to split string into lines with maximum length, without breaking words

I want to break a string up into lines of a specified maximum length, without splitting any words, if possible (if there is a word that exceeds the maximum line length, then it will have to be split).
As always, I am acutely aware that strings are immutable and that one should preferably use the StringBuilder class. I have seen examples where the string is split into words and the lines are then built up using the StringBuilder class, but the code below seems "neater" to me.
I mentioned "best" in the description and not "most efficient" as I am also interested in the "eloquence" of the code. The strings will never be huge, generally splitting into 2 or three lines, and it won't be happening for thousands of lines.
Is the following code really bad?
private static IEnumerable<string> SplitToLines(string stringToSplit, int maximumLineLength)
{
stringToSplit = stringToSplit.Trim();
var lines = new List<string>();
while (stringToSplit.Length > 0)
{
if (stringToSplit.Length <= maximumLineLength)
{
lines.Add(stringToSplit);
break;
}
var indexOfLastSpaceInLine = stringToSplit.Substring(0, maximumLineLength).LastIndexOf(' ');
lines.Add(stringToSplit.Substring(0, indexOfLastSpaceInLine >= 0 ? indexOfLastSpaceInLine : maximumLineLength).Trim());
stringToSplit = stringToSplit.Substring(indexOfLastSpaceInLine >= 0 ? indexOfLastSpaceInLine + 1 : maximumLineLength);
}
return lines.ToArray();
}

Even when this post is 3 years old I wanted to give a better solution using Regex to accomplish the same:
If you want the string to be splitted and then use the text to be displayed you can use this:
public string SplitToLines(string stringToSplit, int maximumLineLength)
{
return Regex.Replace(stringToSplit, #"(.{1," + maximumLineLength +#"})(?:\s|$)", "$1\n");
}
If on the other hand you need a collection you can use this:
public MatchCollection SplitToLines(string stringToSplit, int maximumLineLength)
{
return Regex.Matches(stringToSplit, #"(.{1," + maximumLineLength +#"})(?:\s|$)");
}
NOTES
Remember to import regex (using System.Text.RegularExpressions;)
You can use string interpolation on the match:
$#"(.{{1,{maximumLineLength}}})(?:\s|$)"
The MatchCollection works almost like an Array
Matching example with explanation here

How about this as a solution:
IEnumerable<string> SplitToLines(string stringToSplit, int maximumLineLength)
{
var words = stringToSplit.Split(' ').Concat(new [] { "" });
return
words
.Skip(1)
.Aggregate(
words.Take(1).ToList(),
(a, w) =>
{
var last = a.Last();
while (last.Length > maximumLineLength)
{
a[a.Count() - 1] = last.Substring(0, maximumLineLength);
last = last.Substring(maximumLineLength);
a.Add(last);
}
var test = last + " " + w;
if (test.Length > maximumLineLength)
{
a.Add(w);
}
else
{
a[a.Count() - 1] = test;
}
return a;
});
}
I reworked this as prefer this:
IEnumerable<string> SplitToLines(string stringToSplit, int maximumLineLength)
{
var words = stringToSplit.Split(' ');
var line = words.First();
foreach (var word in words.Skip(1))
{
var test = $"{line} {word}";
if (test.Length > maximumLineLength)
{
yield return line;
line = word;
}
else
{
line = test;
}
}
yield return line;
}

I don't think your solution is too bad. I do, however, think you should break up your ternary into an if else because you are testing the same condition twice. Your code might also have a bug. Based on your description, it seems you want lines <= maxLineLength, but your code counts the space after the last word and uses it in the <= comparison resulting in effectively < behavior for the trimmed string.
Here is my solution.
private static IEnumerable<string> SplitToLines(string stringToSplit, int maxLineLength)
{
string[] words = stringToSplit.Split(' ');
StringBuilder line = new StringBuilder();
foreach (string word in words)
{
if (word.Length + line.Length <= maxLineLength)
{
line.Append(word + " ");
}
else
{
if (line.Length > 0)
{
yield return line.ToString().Trim();
line.Clear();
}
string overflow = word;
while (overflow.Length > maxLineLength)
{
yield return overflow.Substring(0, maxLineLength);
overflow = overflow.Substring(maxLineLength);
}
line.Append(overflow + " ");
}
}
yield return line.ToString().Trim();
}
It is a bit longer than your solution, but it should be more straightforward. It also uses a StringBuilder so it is much faster for large strings. I performed a benchmarking test for 20,000 words ranging from 1 to 11 characters each split into lines of 10 character width. My method completed in 14ms compared to 1373ms for your method.

Try this (untested)
private static IEnumerable<string> SplitToLines(string value, int maximumLineLength)
{
var words = value.Split(' ');
var line = new StringBuilder();
foreach (var word in words)
{
if ((line.Length + word.Length) >= maximumLineLength)
{
yield return line.ToString();
line = new StringBuilder();
}
line.AppendFormat("{0}{1}", (line.Length>0) ? " " : "", word);
}
yield return line.ToString();
}

~6x faster than the accepted answer
More than 1.5x faster than the Regex version in Release Mode (dependent on line length)
Optionally keep the space at the end of the line or not (the regex version always keeps it)
static IEnumerable<string> SplitToLines(string stringToSplit, int maximumLineLength, bool removeSpace = true)
{
int start = 0;
int end = 0;
for (int i = 0; i < stringToSplit.Length; i++)
{
char c = stringToSplit[i];
if (c == ' ' || c == '\n')
{
if (i - start > maximumLineLength)
{
string substring = stringToSplit.Substring(start, end - start); ;
start = removeSpace ? end + 1 : end; // + 1 to remove the space on the next line
yield return substring;
}
else
end = i;
}
}
yield return stringToSplit.Substring(start); // remember last line
}
Here is the example code used to test speeds (again, run on your own machine and test in Release mode to get accurate timings)
https://dotnetfiddle.net/h5I1GC
Timings on my machine in release mode .Net 4.8
Accepted Answer: 667ms
Regex: 368ms
My Version: 117ms

My requirement was to have a line break at the last space before the 30 char limit.
So here is how i did it. Hope this helps anyone looking.
private string LineBreakLongString(string input)
{
var outputString = string.Empty;
var found = false;
int pos = 0;
int prev = 0;
while (!found)
{
var p = input.IndexOf(' ', pos);
{
if (pos <= 30)
{
pos++;
if (p < 30) { prev = p; }
}
else
{
found = true;
}
}
outputString = input.Substring(0, prev) + System.Environment.NewLine + input.Substring(prev, input.Length - prev).Trim();
}
return outputString;
}

An approach using recursive method and ReadOnlySpan (Tested)
public static void SplitToLines(ReadOnlySpan<char> stringToSplit, int index, ref List<string> values)
{
if (stringToSplit.IsEmpty || index < 1) return;
var nextIndex = stringToSplit.IndexOf(' ');
var slice = stringToSplit.Slice(0, nextIndex < 0 ? stringToSplit.Length : nextIndex);
if (slice.Length <= index)
{
values.Add(slice.ToString());
nextIndex++;
}
else
{
values.Add(slice.Slice(0, index).ToString());
nextIndex = index;
}
if (stringToSplit.Length <= index) return;
SplitToLines(stringToSplit.Slice(nextIndex), index, ref values);
}

Replacing character after single quote

I am using the following C# code to modify a lowercase letter to uppercase after a single quote:
public virtual string FirstName
{
get { return _firstName; }
set
{
if (value != null)
{
int pos = value.IndexOf("'", 0);
int strlength = value.Length - 1;
if (pos >= 0 && pos != strlength)
{
string temp = value[pos + 1].ToString();
temp = temp.ToUpper();
value = value.Remove(pos + 1, 1);
value = value.Insert(pos + 1, temp);
}
}
}
}
To me this looks like overkill. Is there an easier way to achieve the desired result:
Value: Mc'donald
Expected: Mc'Donald

here is without regex
int pos = data.IndexOf("'");
if (pos >= 0 && pos < data.Length - 1)
{
StringBuilder sbl = new StringBuilder(data);
sbl[pos + 1] = char.ToUpper(sbl[pos + 1]);
data = sbl.ToString();
}

Since you're open to Regex, would this overload of the Regex.Replace do what you need?
Regex.Replace Method (String, MatchEvaluator)
Here's a modified version of the example given at the link above. I've changed it to use the '\w pattern and to return the match in upper case.
using System;
using System.Text.RegularExpressions;
class RegExSample
{
static string CapText(Match m)
{
// Return the match in upper case
return m.ToString().ToUpperInvariant();
}
static void Main()
{
string text = "Mc'donald";
System.Console.WriteLine("text=[" + text + "]");
Regex rx = new Regex(#"'\w");
string result = rx.Replace(text, new MatchEvaluator(RegExSample.CapText));
System.Console.WriteLine("result=[" + result + "]");
}
}

Perhaps regular expressions?
string value = "Mc'donald";
string found = Regex.Match(value, "'[\\w]").Value;
string result = value.Replace(found, found.ToUpper());
Console.WriteLine(result); // Mc'Donald

How to make next step of a string. C#

The question is complicated but I will explain it in details.
The goal is to make a function which will return next "step" of the given string.
For example
String.Step("a"); // = "b"
String.Step("b"); // = "c"
String.Step("g"); // = "h"
String.Step("z"); // = "A"
String.Step("A"); // = "B"
String.Step("B"); // = "C"
String.Step("G"); // = "H"
Until here its quite easy, But taking in mind that input IS string it can contain more than 1 characters and the function must behave like this.
String.Step("Z"); // = "aa";
String.Step("aa"); // = "ab";
String.Step("ag"); // = "ah";
String.Step("az"); // = "aA";
String.Step("aA"); // = "aB";
String.Step("aZ"); // = "ba";
String.Step("ZZ"); // = "aaa";
and so on...
This doesn't exactly need to extend the base String class.
I tried to work it out by each characters ASCII values but got stuck with strings containing 2 characters.
I would really appreciate if someone can provide full code of the function.
Thanks in advance.
EDIT
*I'm sorry I forgot to mention earlier that the function "reparse" the self generated string when its length reaches n.
continuation of this function will be smth like this. for example n = 3
String.Step("aaa"); // = "aab";
String.Step("aaZ"); // = "aba";
String.Step("aba"); // = "abb";
String.Step("abb"); // = "abc";
String.Step("abZ"); // = "aca";
.....
String.Step("zzZ"); // = "zAa";
String.Step("zAa"); // = "zAb";
........
I'm sorry I didn't mention it earlier, after reading some answers I realised that the problem was in question.
Without this the function will always produce character "a" n times after the end of the step.

NOTE: This answer is incorrect, as "aa" should follow after "Z"... (see comments below)
Here is an algorithm that might work:
each "string" represents a number to a given base (here: twice the count of letters in the alphabet).
The next step can thus be computed by parsing the "number"-string back into a int, adding 1 and then formatting it back to the base.
Example:
"a" == 1 -> step("a") == step(1) == 1 + 1 == 2 == "b"
Now your problem is reduced to parsing the string as a number to a given base and reformatting it. A quick googling suggests this page: http://everything2.com/title/convert+any+number+to+decimal
How to implement this?
a lookup table for letters to their corresponding number: a=1, b=2, c=3, ... Y = ?, Z = 0
to parse a string to number, read the characters in reverse order, looking up the numbers and adding them up:
"ab" -> 2*BASE^0 + 1*BASE^1
with BASE being the number of "digits" (2 count of letters in alphabet, is that 48?)
EDIT: This link looks even more promising: http://www.citidel.org/bitstream/10117/20/12/convexp.html

Quite collection of approaches, here is mine:-
The Function:
private static string IncrementString(string s)
{
byte[] vals = System.Text.Encoding.ASCII.GetBytes(s);
for (var i = vals.Length - 1; i >= 0; i--)
{
if (vals[i] < 90)
{
vals[i] += 1;
break;
}
if (vals[i] == 90)
{
if (i != 0)
{
vals[i] = 97;
continue;
}
else
{
return new String('a', vals.Length + 1);
}
}
if (vals[i] < 122)
{
vals[i] += 1;
break;
}
vals[i] = 65;
break;
}
return System.Text.Encoding.ASCII.GetString(vals);
}
The Tests
Console.WriteLine(IncrementString("a") == "b");
Console.WriteLine(IncrementString("z") == "A");
Console.WriteLine(IncrementString("Z") == "aa");
Console.WriteLine(IncrementString("aa") == "ab");
Console.WriteLine(IncrementString("az") == "aA");
Console.WriteLine(IncrementString("aZ") == "ba");
Console.WriteLine(IncrementString("zZ") == "Aa");
Console.WriteLine(IncrementString("Za") == "Zb");
Console.WriteLine(IncrementString("ZZ") == "aaa");

public static class StringStep
{
public static string Next(string str)
{
string result = String.Empty;
int index = str.Length - 1;
bool carry;
do
{
result = Increment(str[index--], out carry) + result;
}
while (carry && index >= 0);
if (index >= 0) result = str.Substring(0, index+1) + result;
if (carry) result = "a" + result;
return result;
}
private static char Increment(char value, out bool carry)
{
carry = false;
if (value >= 'a' && value < 'z' || value >= 'A' && value < 'Z')
{
return (char)((int)value + 1);
}
if (value == 'z') return 'A';
if (value == 'Z')
{
carry = true;
return 'a';
}
throw new Exception(String.Format("Invalid character value: {0}", value));
}
}

Split the input string into columns and process each, right-to-left, like you would if it was basic arithmetic. Apply whatever code you've got that works with a single column to each column. When you get a Z, you 'increment' the next-left column using the same algorithm. If there's no next-left column, stick in an 'a'.

I'm sorry the question is stated partly.
I edited the question so that it meets the requirements, without the edit the function would end up with a n times by step by step increasing each word from lowercase a to uppercase z without "re-parsing" it.
Please consider re-reading the question, including the edited part

This is what I came up with. I'm not relying on ASCII int conversion, and am rather using an array of characters. This should do precisely what you're looking for.
public static string Step(this string s)
{
char[] stepChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
char[] str = s.ToCharArray();
int idx = s.Length - 1;
char lastChar = str[idx];
for (int i=0; i<stepChars.Length; i++)
{
if (stepChars[i] == lastChar)
{
if (i == stepChars.Length - 1)
{
str[idx] = stepChars[0];
if (str.Length > 1)
{
string tmp = Step(new string(str.Take(str.Length - 1).ToArray()));
str = (tmp + str[idx]).ToCharArray();
}
else
str = new char[] { stepChars[0], str[idx] };
}
else
str[idx] = stepChars[i + 1];
break;
}
}
return new string(str);
}

This is a special case of a numeral system. It has the base of 52. If you write some parser and output logic you can do any kind of arithmetics an obviously the +1 (++) here.
The digits are "a"-"z" and "A" to "Z" where "a" is zero and "Z" is 51
So you have to write a parser who takes the string and builds an int or long from it. This function is called StringToInt() and is implemented straight forward (transform char to number (0..51) multiply with 52 and take the next char)
And you need the reverse function IntToString which is also implementet straight forward (modulo the int with 52 and transform result to digit, divide the int by 52 and repeat this until int is null)
With this functions you can do stuff like this:
IntToString( StringToInt("ZZ") +1 ) // Will be "aaa"

You need to account for A) the fact that capital letters have a lower decimal value in the Ascii table than lower case ones. B) The table is not continuous A-Z-a-z - there are characters inbetween Z and a.
public static string stepChar(string str)
{
return stepChar(str, str.Length - 1);
}
public static string stepChar(string str, int charPos)
{
return stepChar(Encoding.ASCII.GetBytes(str), charPos);
}
public static string stepChar(byte[] strBytes, int charPos)
{
//Escape case
if (charPos < 0)
{
//just prepend with a and return
return "a" + Encoding.ASCII.GetString(strBytes);
}
else
{
strBytes[charPos]++;
if (strBytes[charPos] == 91)
{
//Z -> a plus increment previous char
strBytes[charPos] = 97;
return stepChar(strBytes, charPos - 1); }
else
{
if (strBytes[charPos] == 123)
{
//z -> A
strBytes[charPos] = 65;
}
return Encoding.ASCII.GetString(strBytes);
}
}
}
You'll probably want some checking in place to ensure that the input string only contains chars A-Za-z
Edit Tidied up code and added new overload to remove redundant byte[] -> string -> byte[] conversion
Proof http://geekcubed.org/random/strIncr.png

This is a lot like how Excel columns would work if they were unbounded. You could change 52 to reference chars.Length for easier modification.
static class AlphaInt {
private static string chars =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
public static string StepNext(string input) {
return IntToAlpha(AlphaToInt(input) + 1);
}
public static string IntToAlpha(int num) {
if(num-- <= 0) return "a";
if(num % 52 == num) return chars.Substring(num, 1);
return IntToAlpha(num / 52) + IntToAlpha(num % 52 + 1);
}
public static int AlphaToInt(string str) {
int num = 0;
for(int i = 0; i < str.Length; i++) {
num += (chars.IndexOf(str.Substring(i, 1)) + 1)
* (int)Math.Pow(52, str.Length - i - 1);
}
return num;
}
}

LetterToNum should be be a Function that maps "a" to 0 and "Z" to 51.
NumToLetter the inverse.
long x = "aazeiZa".Aggregate((x,y) => (x*52) + LetterToNum(y)) + 1;
string s = "";
do { // assertion: x > 0
var c = x % 52;
s = NumToLetter() + s;
x = (x - c) / 52;
} while (x > 0)
// s now should contain the result