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c# replace string with many "x" [duplicate]

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Best way to repeat a character in C#
(21 answers)
Closed 1 year ago.
I am writing a windows form app in C#. I have a label with a random word, e.g. "computer". User has to guess what is this word by guessing letter by letter. But word "computer" must be replaced with as many "x" as there is letters in a word, so in this example user should see "xxxxxxxx".
I tried to replace it with regex like this:
private void Form1_Load(object sender, EventArgs e)
{
word.Text = Regex.Replace(word.Text, #"^[a-zA-Z]+$", "x");
}
But it only replace with single "x".
I also tried with for loop, but the result is the same:
private void Form1_Load(object sender, EventArgs e)
{
for (int i = 0; i <= word.Text.Length; i++)
{
word.Text = Regex.Replace(word.Text, #"^[a-zA-Z]+$", "x");
}
}

You can create a new string of "x" repeated the number of characters in your word. No need for regexes.
word.Text = new string('x', word.Text.Length);

Approach without RegEx
string wordText = "computer";
wordText = string.Concat(wordText.Select(x => char.IsLetter(x) ? 'x' : x));
if you want to stay with RegEx, replace #"^[a-zA-Z]+$" with "[a-zA-Z]" to match every single character

Try this:
word.Text=String.Join("",word.Text.Select(s=>s='x').ToArray());

Text to pig latin translator inserts duplicate characters

I'm creating a c# Windows Forms app to convert English Text to Pig Latin, but the program is inserting the first letter (if it's a consonant) five times in the end, instead of just one.
I was able to insert "way" at the end of the text by using an if statement, that checks if the first letter is a vowel. However, my issue starts when it checks if a word is not a vowel.
string[] vowels = new string[5] { "a", "e", "i", "o", "u" };
private void BtnTranslate_Click(object sender, EventArgs e)
{
string TextEnglish = txtEnglish.Text;
for (int i = 0; i < vowels.Length; i++)
{
if (TextEnglish.StartsWith(vowels[i]))
{
TextEnglish = TextEnglish.Insert(TextEnglish.Length, "way");
}
else if(!TextEnglish.StartsWith(vowels[i]))
{
string TextEnglishSubstring = TextEnglish.Substring(0, 1);
TextEnglish = TextEnglish.Insert(TextEnglish.Length, TextEnglishSubstring);
TextEnglish = TextEnglish.Insert(TextEnglish.Length, "ay");
}
//string substringToInsert = TextEnglish.Substring(0, 1);
//TextEnglish = TextEnglish.Insert(TextEnglish.Length, "c");
txtPigLatin.Text = TextEnglish;
}
}

First I might recommend that you create a separate method for returning a pig-latin translation, and then call that method from your button click event. This allows for better code re-use and will result in cleaner code.
The problem is that you're looping over all the items in the vowels array and changing the text for each iteration. Instead what you want to do is simply determine if the word starts with a vowel or not. Again, this could be written in another method (more code encapsulation, which means this can also be re-used elsewhere if needed).
Note that I've written the vowels as a string, but can treat it as a char[] (because that's kind of what strings really are), and the trick here is to see if the array Contains the first character of the input string:
public static bool BeginsWithAVowel(string input)
{
if (string.IsNullOrWhiteSpace(input)) return false;
var vowels = "AaEeIiOoUu";
return vowels.Contains(input.Substring(0, 1));
}
Now, we can use this method to test our string in our pig latin conversion method:
public static string ConvertToPigLatin(string input)
{
if (string.IsNullOrWhiteSpace(input)) return input;
if (BeginsWithAVowel(input))
{
// Add "way" to the end of the string and return it
return input + "way";
}
// Remove the first character and add it, plus "ay", to the end and return it
return input.Substring(1) + input.Substring(0, 1) + "ay";
}
Now, in the button click event, all we have to do to convert the text is call our method with the original text and then set the Text property to the result:
private void BtnTranslate_Click(object sender, EventArgs e)
{
txtPigLatin.Text = ConvertToPigLatin(txtEnglish.Text);
}

You're checking the first character against each possible vowel, and it can't possibly by all of them, and you're running the code to convert once for each vowel checked.
Instead, you should check if it's a vowel first, set a flag, then do your conversion logic. There are a few ways to manage this, here's an example:
string TextEnglish = txtEnglish.Text;
bool startsWithVowel = vowels.Any(v => TextEnglish.StartsWith(v));
if(startsWithVowel)
{
// Do vowel logic
}
else
{
// Do consonant logic
}

TextBox text "Replace" function does not work well

I have already looked at similar questions here but it did not help.
I am using windows forms. I have button1 and textbox1.
I am trying to replace (or delete) the selected text in textBox1 and enter new letter (letter A) in place of it.
The code works well with random mixed numbers and letters
for example:
385F1 select 8 and then result = 3A5F1 (8 replaced by A)
H74S31B select 4S and then the result is = H7A31B
KQ5689 select Q5689 and then the result is KA
So it works well, but when I select a number or a letter from a string which consists of same numbers or letters then it does not work, for example:
666777222333 select any 7 then the result = 666AAA222333 (not
working)
9992244GG select any 9 then the result = AAA2244GG (not working)
QQQHHHUUU select any Q then the result = AAAHHHUUU (not working)
QQQHHHUUU select any QH then the result = QQAHHUUU(it works when
different letters selected)
4433366 select 333 then the result = 44A66 (it works when all same
numbers is selected)
Hope I explained it well. I don't know what causes this behavior. please help. Thank you
public partial class Form1 : Form
{
int TxTindex;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
ActiveControl = textBox1;
textBox1.Focus();
}
private void button1_Click(object sender, EventArgs e)
{
textBox1.Focus();
if (textBox1.SelectedText.Length > 0) // to check if any text selected
{
TxTindex = textBox1.SelectionStart; // save the caret position
textBox1.Text = textBox1.Text.Replace(textBox1.Text.Substring(textBox1.SelectionStart, textBox1.SelectionLength),"A");
textBox1.SelectionStart = TxTindex + 1; // place the caret after the inserted string
}
else
{
return;
}
}
}

Your problem is here :
textBox1.Text = textBox1.Text.Replace(textBox1.Text.Substring(textBox1.SelectionStart, textBox1.SelectionLength),"A");
The Substring function returns string. In your example (666777222333 select any 7 then the result = 666AAA222333 (not working)), it returns "7". But Text.Replace will replace all occurrences of 7. That is not what you want. What you can do is, instead of using string.Replace function, use string.Remove and string.Insert
textBox1.Text = textBox1.Text.Remove(textBox1.SelectionStart, textBox1.SelectionLength).Insert(textBox1.SelectionStart, "A");
But this might not be very efficient for large strings. A StringBuilder would be better.

The problem is caused by the usage of string.Replace function.
What you are trying to accomplish can be done simply by
if (textBox1.SelectionLength > 0)
textBox1.SelectedText = "A";
There is no need to save/set selection start.

Select Text in a multiline textbox, move it to another multiline textbox on a button click in C#

I have a problem that I haven't come across yet that I hope some of you may help me with. I am trying to select a single line, either the fist, second, or last line in a multiline textbox and move it to another multiline textbox with a button click in C#. I am unsure how to select just a single line at a time, then add it to the other multiline textbox. If anyone has some insight, that would be great! Thank you!
Brent

Well, assuming that you are defining a "line" as a complete string of characters separated by other similar strings with a newline character, and not simply as the string of characters visible in a single horizontal plane in a text field with word wrap property set to true.....
public void Button1_Click(object sender, ClickEventArgs e)
{
//get the values of both boxes
string value1 = TextBox1.Text.Trim();
string value2 = TextBox2.Text.Trim();
//split the value from the source box on its new line characters
string[] parts = value1.split(Environment.NewLine);
string last_line = parts[parts.length -1];
//add the last row from the source box to the destination box
value2 += (Environment.NewLine + last_line);
//set the last_line in the source to an empty string
parts[parts.Length -1] = String.Empty;
//put the new values back in their text boxes
TextBox1.Text = String.Join(Environment.NewLine, parts).Trim();
TextBox2.Text = value2;
}
If you are dealing with visible line and word wrapped that is a whole 'nother ball game and the answer is dependant on if you are talking ASP, or Win App. Also, this was written off the cuff, so you may need to tweak a character or two to get it to compile. No Warranties, LOL.

Something like this will work:
public void Button1_Click(object sender, ClickEventArgs e)
{
string text = TextBox1.Text;
// spliting text on the basis on newline.
string[] myArray = text.Split(new char[] { '\n' });
foreach (string s in myArray)
{
//Line by line copy
TextBox2.Text += s;
}
}

Try something like this:
private void button1_Click(object sender, EventArgs e)
{
if (textBox1.Lines.Length > 0)
{
textBox2.Text += textBox1.Lines[textBox1.GetLineFromCharIndex(textBox1.SelectionStart)];
}
}
What it is doing is using the GetLineFromCharIndex with the SelectionStart caret location as the char Index to pull the Line out of the TextBox.Lines array

How to let the textbox drop strings started with an Arabic character (semi each other) as it does in capital and small characters in default language?

In textbox autocomplete properties when i entered a character like 'm' it dropped all strings start with 'm' or 'M' but when i write a character 'أ' (this is an Arabic character) it dropped only string start with 'أ' , I want when i typed 'أ' or 'ا' or 'إ' or 'آ' it drop all strings start with any character from those not the typed character only , in C# windows application I'm not using ASP.net
Any suggestions????

I am quite surprised to see that neither the text box control nor the auto complete string collection has a way to specify what defines string equality for the auto-complete mechanism. The only way I can think of to get the behavior that you want would be to create your own auto-complete mechanism.
I have done this several times in the past, before the functionality was supplied by the framework, and it is not difficult.
Just use an editable ComboBox instead of a TextBox, and handle the TextChanged event to create the autocompletions.
Here is some untried pseudocode of the procedure:
bool textChangedProgramatically = false;
List<string> myStrings; // The list of items that can appear in the auto-complete.
private static myComboBox_TextChanged(object sender, EventArgs args)
{
if (textChangedProgramatically)
return;
string searchText = myComboBox.Text;
// Use appropriate culturally-sensative string StartsWith comparisons
List<string> matchingItems = GetMatchingStrings(searchText, myStrings);
string firstMatch;
if (matchingItems.Length > 0)
firstMatch = matchingItems[0];
else
firstMatch = string.Empty;
myComboBox.Items.Clear;
myComboBox.Items.AddRange(matchingItems);
string fulltext = searchText;
if (firstMatch.Length > fullText.Length)
{
fullText = fullText + firstMatch.Substring(fullText.Length);
textChangeProgramatically = true;
myComboBox.Text = fullText;
myComboBox.SelectionStart = searchText.Length;
myComboBox.SelectionLength = fullText.Length - searchText.Length;
textChangeProgramatically = false;
}
}
The trick is to get the right matching behavior in GetMatchingStrings. You may want to use string compatibility normalization to get the Arabic characters into non-presentation forms before doing the comparison, but I expect the right SubString overload might handle all of these cases for you.