How to update the text from the TextBox control?
Consider a TextBox that already contains the string "Wel"
To insert text in the TextBox, I use:
TextBox1.Text = TextBox1.Text.Insert(3, "come")
And to remove characters from the TextBox:
TextBox1.Text = TextBox1.Text.Remove(3, 4)
But I need to be able to do this:
TextBox1.Text.Insert(3, "come");
TextBox1.Text.Remove(3, 4);
However, this code doesn't update the TextBox.
It this possible?
Can this be accomplished via the append method?
Text property of TextBox is of type string which is immutable it's not possible to change the existing string. Insert() or Remove() returns a new instance of string with the modification and you will have to assign this new instance back to TextBox's Text property.
There is TextBox.AppendText() that you might be interested in. It appends text to the end of the string but you cannot do anything like Insert() or Remove() with it though.
EDIT:
for your keypress, you could do something like this
char charToReplace = (char) (e.KeyChar + 1); // substitute replacement char
textBox1.SelectedText = new string(charToReplace,1);
e.Handled = true;
'string' is a immutable type, so each time string value changes new memory is allocated. So if you want to insert or remove text from TextBox, you have to assign it back to TextBox.Text property. However, if you just want to append text to the TextBox.Text, you can do
textBox.AppendText("Hello");
Related
at line 161,I want to insert my text in parameter t,but it won't change when i debug it.although the parameter tmp had alredy changed.
I want to change this Text in UI,when my parameter t changes.
With respect to your specific issue, Insert is defined as:
public string Insert (int startIndex, string value);
and returns a new string. In C#, strings aren't modified, new strings are created. In this way, they act like a value type, even though they're a reference type. In other words, once a string is created, it is never modified - it's 'immutable'. So, you need to store your newly created string.
In cases like this, I like to use the string interpolation, as it allows me to get a slightly clearer representation of what the final string will look like.
var tmp = System.Text.Encoding.UTF8.GetString ( e.Message );
t.text = $"{tmp}\n{t.text}"; // Note that a newline is represented as \n
Or, if you add the System.Text namespace; you could reduce it down to:
using System.Text;
...
t.text = $"{Encoding.UTF8.GetString ( e.Message )}\n{t.text}";
The string type in c# is immutable, therefore Insert returns a new string instead of modifying the current one.
Do:
t = t.text.Insert(0, tmp + "//n");
See also
How to modify string contents in C#
I am very new to coding, so this is likely a simple answer. I am trying to get my GUI button in C# to display the total of an arithmetic function I wrote. For example:
int totalGold = goldOnHand + earnedGold;
I have tried to display the totalGold as such in a text box name TxtGold:
private void BtnSplit_Click(object sender, EventArgs e) {
TxtGold.Text = "totalGold";
}
The text box only displays: totalGold
How do I get the textbox to display the integer that represents the total amount of gold instead of the phrase totalGold?
Thanks for any help from someone willing to give a hand to a noob!
In this code
int totalGold = goldOnHand + earnedGold;
You created a variable called totalGold. And you want to display it in a text box. That's so far so good. But when you try to set the text, things went wrong. You set the text of the text box to "totalGold".
In C#, "" means a string literal. Its value is "What you see is what you get". So when you say "totalGold", it displays the word totalGold. What you need to do is to remove the "" so that totalGold turns into a variable.
TxtGold.Text = totalGold;
But totalGold is an integer! you can only set the text of a text box using a string! How to convert from an integer to a string? Simple, use the ToString() method!
TxtGold.Text = totalGold.ToString();
Turn it into a string using the ToString() method:
TxtGold.Text = totalGold.ToString();
WHY:
What you were doing is setting the text of the button to a string literal, not the value of the variable.
Additionally, you cannot set TxtGold.Text to the integer, because it is a string property (see MSDN). Therefore, you have to do a ToString() to convert the integer to a string.
TxtGold.Text = "totalGold"; will print the string "totalGold" in your text box. If you need to print the integer value assigned to variable totalGold you have to print it as shown below
TxtGold.Text = totalGold.ToString();//that is, avoid the double quotes
the full code might be as follows
private void BtnSplit_Click(object sender, EventArgs e) {
int totalGold = goldOnHand + earnedGold;
TxtGold.Text = totalGold.ToString();
}
I have been editing some long existing code to implement some new functionality. this requires replacing a textbox with a richtextbox whilst keeping the existing implementation the same. the rich text box had comparable properties to the textbox until i got to the caretindex. The original line (which worked for a textbox) was:
this.ViewModel.Body = this.ViewModel.Body.Insert(this.txtEditor.CaretIndex, link);
so when i changed "txtEditor" to a richtextbox i implemented this:
this.ViewModel.Body = this.ViewModel.Body.Insert(this.txtEditor.CaretPosition, link);
i believe these are similar however "Caret Position" is of type TextPointer whereas "CaretIndex" was an integer and the Body.Insert method will only take an integer as its first parameter.
Is there any way to convert a TextPointer to and Integer and if so, how is it done?
Thanks
It is somewhat convoluted, but it is possible to get the caret index using some hacks:
var start = txtEditor.Document.ContentStart;
var here = txtEditor.CaretPosition;
var range = new TextRange(start, here);
int indexInText = range.Text.Length;
To use:
this.ViewModel.Body = this.ViewModel.Body.Insert(indexInText, link);
How can I write the half-space character in c# in a Textbox (not Console.Writleline statement) ? Is there a specific char code for it?
Unicode THINSPACE U+2009 is a perfectly ordinary character, try:
TextBox.Text += '\u2009';
I don't know what you mean by half-space, but Char.Parse() will probably do what you want. Please get a list of Unicode spaces
Then do this (example is for 1/2 en space; remove all plus signs):
string UnicodeString = "\u2000"; // U+2000
TextBox.Text = Char.Parse(UnicodeString);
However, you probably don't need Char.Parse() for this. You could simply do this:
string halfSpace = "\u2000"; // So you can reuse it
TextBox.Text = halfSpace;
UPDATE: If you want to add it to the TextBox (+=), rather than replacing the whole line (=), use this:
TextBox.Text += halfSpace
OK I have a text box with a set value, I only want this set value sent if the text box is not filled in on completion of form.
code
dontaion_euro.Text = "99.00";
problem is when I click send it only sends the data 99.00 I only want this sent if blank.
how could I achieve this?
Step1 : you need to Trim the Textbox value to remove the white spaces.
Step2 : you can compare the Textbox value with Empty String to check whether Textbox value is Empty or not
Try this:
if(donation_euro.Text.Trim().Equals(""))
{
donation_euro.Text="99.00";
}
If I understand correctly, you can use String.IsNullOrEmpty method like;
Indicates whether the specified string is null or an Empty string.
if(string.IsNullOrEmpty(dontaion_euro.Text))
{
dontaion_euro.Text = "99.00";
}
else
{
//Your textbox is not null or empty
}