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How can I make a TextBox in C# to allow a maximum of one . (dot)?
Thus, abcdef and abc.def would be valid inputs whereas ab.cd.ef wouldn't.
By allow I mean that the user should not be able to enter a dot if there is already one in the text field.
Java has DocumentFilters for that purpose, is there something similar in C#?
I guess this is for validating user inputs. You should create a button and tell the user when he is done, press it so that you can check whether there is only one . in the string.
Assumptions:
Let your text box be called tb. Let your button's Click event handler be BtnOnClick.
Now we can start to write code. First create the handler:
private void BtnOnClick (object sender, EventArgs e) {
}
In the handler, you need to loop through the string and check each character. You can use a foreach for this:
int dotCount = 0;
string s = tb.Text;
if (s.StartsWith(".")) //starts with .
//code to handle invalid input
return;
if (s.EndsWith(".")) //ends with .
//code to handle invalid input
return;
foreach (char c in s) {
if (c == '.') {
dotCount++;
}
if (dotCount >= 2) { //more than two .
//code to handle invalid input
return;
}
}
// if input is valid, this will execute
Alternatively, you can use a query expression. But I think you are unlikely to know what that is.
string s = tb.Text;
if (s.StartsWith(".")) //starts with .
//code to handle invalid input
return;
if (s.EndsWith(".")) //ends with .
//code to handle invalid input
return;
var query = from character in s
where character == '.'
select character;
if (query.Count() > 1) {
//code to handle invalid input
return;
}
// if input is valid, this will execute
Related
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I'm creating a unity quiz game using input fields.
How can I use text from an input field to match with an answer in a c# script?
hijinxbassist's example is good, however, i made an example that includes the other parts as well, like adding event listeners and declaring the fields.
Checking for single correct answer:
public Button submitAnswerBtn; // assign a UI button object in editor
public InputField answerInput; // assign a UI inputfield object in editor
private string a1_right_answer = "foo"; // make it public and edit the answer in editor if you like
private void Awake()
{
// add event listener when button for submitting answer is clicked
submitAnswerBtn.onClick.AddListener(() => {
// validate the answer
if(answerInput.text.ToLower() == a1_right_answer) {
// success
Debug.Log("Correct");
} else {
Debug.Error("Wrong");
}
});
Checking for multiple correct answers:
public Button submitAnswerBtn; // assign a UI button object in editor
public InputField answerInput; // assign a UI inputfield object in editor
private string[] a1_right_answers = { "foo", "bar", "foo1", "bar1" }; // multiple right answers
private bool is_right_answer = false; // default value
private void Awake()
{
// add event listener when button for submitting answer is clicked
submitAnswerBtn.onClick.AddListener(() => {
// loop through all the right answers
for (int i = 0; i < a1_right_answers.Length; i++)
{
// validate the answer
if(answerInput.text.ToLower() == a1_right_answers[i]) {
// success
is_right_answer = true;
break;
}
}
// check if the user got the right or wrong answer
if(is_right_answer) {
Debug.Log("Correct");
is_right_answer = false; // reset for next guess
}
else {
Debug.Log("Wrong");
// no need to reset 'is_right_answer' since its value is already default
}
});
I am not sure which part of this problem you are stuck on, but I will attempt to answer.
I think the most important thing when comparing an input field with a stored answer is to make sure the comparison is case insensitive. You can do this by converting both texts to either lowercase or uppercase.
var usersAnswer = answerInputField.text.ToLower();
var actualAnswer = "Some Answer".ToLower();
if (usersAnswer == actualAnswer)
{
Debug.Log("You got it right!");
}
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I have the following code:
private void G1_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
{
decimal quantity = 0, cost = 0;
decimal totalstock = 0, newtotalstock = 0;
if (decimal.TryParse(G1.Rows[e.RowIndex].Cells["RealExport"].Value.ToString(), out quantity) && decimal.TryParse(G1.Rows[e.RowIndex].Cells["Cost"].Value.ToString(), out cost))
{
decimal price = quantity * cost;
G1.Rows[e.RowIndex].Cells["Total"].Value = price.ToString();
}
if (decimal.TryParse(G1.Rows[e.RowIndex].Cells["TotalStock"].Value.ToString(), out totalstock) && decimal.TryParse(G1.Rows[e.RowIndex].Cells["RealExport"].Value.ToString(), out quantity))
{
newtotalstock = totalstock - quantity;
G1.Rows[e.RowIndex].Cells["TotalStock"].Value = newtotalstock.ToString();
return;
}
decimal avai = 0, newavai = 0;
if (decimal.TryParse(G1.Rows[e.RowIndex].Cells["RealExport"].Value.ToString(), out quantity) && decimal.TryParse(G1.Rows[e.RowIndex].Cells["AvailableStock"].Value.ToString(), out avai))
{
newavai = avai - quantity;
G1.Rows[e.RowIndex].Cells["AvailableStock"].Value = newavai.ToString();
return;
} }
The problem is, it only execute 2 out of 3 the code, I mean, when the newtotalstock is calculated, the code will end.
I try to change the newavai to up above, and the result is the same, it will calculate the newavai and pass the newtotalstock. I dont know why, all the code are correct. Please help
word "return" ends function, if you are using void type method you don't really need to use return, unless you want to quit it at certain point. The code after "return" will never be executed (only exception might be during usage "yield return", but that is another story).
void someMethod()
{
doSomething();
return;
StartWorldWarThree(); //no waries, this will never be executed :)
}
Furethermore you can always make a breakpoint in your code (click on the left border of your window, or just read about it) and then check how your code is being executed :) F10/F11 to make step in your code, F5 to go to next breakpoint or end execution, if there are no more breakpoints.
Taking in count that all conditions are true the return; will stop executing the rest of the code, if you want the 3 if to be executed, remove the return; and place it the last line of the method as
void Method() {
if() {}
if() {}
if() {}
return;
}
Or dont place it at all, because that method is void and does not need it
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I am developing a project in C#, for which I want to login/authenticate a user using their fingerprint.
I bought a ZK4500 Fingerprint scanner and got its SDK from http://www.zkteco.com/product/ZK4500_238.html. The SDK is in C++.
So How can I integrate this SDK with my C# project to perform the desired functionality?
You need to add reference to ZKFPEngXControl that will appear under COM Type Libraries. After that you can use the ZKFPEngX Class to do whatever you require.
using ZKFPEngXControl;
and then
ZKFPEngX fp = new ZKFPEngX();
fp.SensorIndex = 0;
fp.InitEngine(); // Do validation as well as it returns an integer (0 for success, else error code 1-3)
//subscribe to event for getting when user places his/her finger
fp.OnImageReceived += new IZKFPEngXEvents_OnImageReceivedEventHandler(fp_OnImageReceived);
You can write your own method fp_OnImageReceived to handle the event. for example you can write this in that method;
object imgdata = new object();
bool b = fp.GetFingerImage(ref imgdata);
Where imgdata is an array of bytes.You can also use other methods in ZKFPEngX, to achieve your goals. Remember to close the engine when form closes.
fp.EndEngine();
You can store a fingerprint under OnEnroll(bool ActionResult, object ATemplate) Event.This event will be called when BeginEnroll() has been executed.
//Add an event handler on OnEnroll Event
ZKFPEngX x = new ZKFPEngX();
x.OnEnroll += X_OnEnroll;
private void X_OnEnroll(bool ActionResult, object ATemplate)
{
if (ActionResult)
{
if (x.LastQuality >= 80) //to ensure the fingerprint quality
{
string regTemplate = x.GetTemplateAsStringEx("9");
File.WriteAllText(Application.StartupPath + "\\fingerprint.txt", regTemplate);
}
else
{
//Quality is too low
}
}
else
{
//Register Failed
}
}
You can try to verify the fingerprints under OnCapture(bool ActionResult, object ATemplate)event. This event will be called when a finger is put on the scanner.
Add an event handler on OnCapture Event:
x.OnCapture += X_OnCapture;
Verify the fingerprints when the event has been called (a finger is put on the scanner):
private void X_OnCapture(bool ActionResult, object ATemplate)
{
if (ActionResult) //if fingerprint is captured successfully
{
bool ARegFeatureChanged = true;
string regTemplate = File.ReadAllText(Application.StartupPath + "\\fingerprint.txt");
string verTemplate = x.GetTemplateAsString();
bool result = x.VerFingerFromStr(regTemplate , verTemplate, false, ARegFeatureChanged);
if (result)
{
//matched
}
else
{
//not matched
}
}
else
{
//failed to capture a valid fingerprint
}
}
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I want to make a Code Editing control that can format text somewhat like Visual Studio,till now i have implemented syntax highlighting and autocompletion but i want to format text in nested curly braces.For example:Consider a for loop,
for(int i=0;i<=10;i++)
{
Function_One(); //This should be a tab away from first brace
Function_Two(); //So with this
if(a==b) //So with this
{ //This should be four tabs away from first brace
MessageBox.Show("Some text");//This should be six tabs away from first brace
} //This should be four tabs away from first brace
}
now what i want is that this should look something like this,
for(int i=0;i<=10;i++)
{
Function_One();
Function_Two();
if(a==b)
{
MessageBox.Show("Some text");
}
}
I have already tried Regular Expressions but at some point they fail to match,so i tried to match it with code but code cannot match very deeply nested code or is very hard to implement
,so is there any way to achieve this,and one more thing i am doing all this in Winforms control RichTextBox using C#.
This is by no means a simple feat, I am unaware of any tools or plugins that you would be able to take advantage of, my only recommendation is to research Monodevelop's implementation of this.
See MonoDevelop's github for details.
I think the best way to implement this would be to create some global variables for your form:
private int _nestedBracketCount = 0;
private const string TabString = " ";
private const int TabSpaces = 4;
And then handle all of it in a KeyPressed event handler for the rich text box:
private void richTextBox1_OnKeyPress(object sender, KeyPressEventArgs e) {
var currentLength = richTextBox1.Text.Length;
if (e.KeyChar == '{') {
// need to increment bracket counter
_nestedBracketCount++;
} else if (e.KeyChar == '}') {
// remove last #(TabSpaces) characters from the richtextbox
richTextBox1.Text.Remove(currentLength - TabSpaces);
_nestedBracketCount--;
richTextBox1.AppendText("}");
e.Handled = true;
} else if (e.KeyChar == (char)13) {
// append newline and correct number of tabs.
var formattedSpaces = string.Empty;
for (var i = 0; i < _nestedBracketCount; i++)
formattedSpaces += TabString;
richTextBox1.AppendText("\n" + formattedSpaces);
e.Handled = true;
}
}
I think this should provide you with a halfway decent starting point.
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want to ask about void type, so I could know that it works or no
in PHP i could have a condition like this:
if(mysql_query($query))
{ bla bla }
else
{ print error }
how to do like that on ASP.NET?
i'm trying like this:
if (k.EditPassword(username.Text, oldPassTxt.Text, newPassTxt.Text) == true )
{
Response.Redirect("sample.aspx");
}
else
{ print error }
but of course, it cannot be like that, because void isn't boolean
Usually void functions that do work that can fail will have some other way of informing you that they failed. Often they will throw an Exception:
try
{
k.EditPassword(...)
}
catch(ApplicationException ex)
{
// print Exception
}
Response.Redirect(...)
Other times they will set a status variable or something:
k.EditPassword(...)
if (k.Result == Result.OK)
Response.Redirect(...)
else
// print error...
Looking at documentation or source code for the conditions you are trying to handle is the only way to know how to handle it.
You can use a literal control and add your text to it. So your code will go something like,
if (k.EditPassword(username.Text, oldPassTxt.Text, newPassTxt.Text) == true )
{
Response.Redirect("sample.aspx");
}
else
{ Literal1.Text = error; }
Literal should be in design file, you can add it from toolbox.
But a better and proper way would be to,
Log it. (You would need a log mecahnism)
Write a unit test :)