I'm new to programming and I have a problem. I have two buttons and a textbox. When I press the button, a number will show on the textbox, but when I press the second button the number in the textbox overwrites it and replaces it instead of adding to it in the textbox. How do I fix this? I want the values to add instead of replacing it.
public partial class Form1 : Form
{
int value1 = 0;
int value2 = 0;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
value1++;
textBox1.Text = value1.ToString();
}
private void button2_Click(object sender, EventArgs e)
{
value2 += 2;
textBox1.Text = value2.ToString();
}
}
}
If you want to add two integers and assign the result back to textBox1 you have to
Parse textBox1.Text to integer: int.Parse(textBox1.Text)
Sum up values: int.Parse(textBox1.Text) + value2
Convert the outcome back to string: (...).ToString()
Implementation:
private void button2_Click(object sender, EventArgs e) {
value2 += 2;
textBox1.Text = (int.Parse(textBox1.Text) + value2).ToString();
}
Edit: If there's a possibility that textBox1.Text doesn't contain a valid integer value (say, textBox1.Text is empty) you can use int.TryParse:
private void button2_Click(object sender, EventArgs e) {
if (int.TryParse(textBox1.Text, out var v)) {
value2 += 2;
textBox1.Text = (v + value2).ToString();
}
else {
//TODO: textBox1.Text is not a valid integer; put relevant code here
}
}
You're using two separate variables (value1 and value2 above) to store the results of each button click, depending in which button was clicked. Think of it like this:
On program start:
value1 = 0
value2 = 0
User clicks button 1, which executes button1_Click. This increments value1 (via value1++), so the two variables look like this:
value1 = 1
value2 = 0
User then clicks button 2, which executes button2_Click. This sets value2 to whatever was previously in value2 + 2. However, note that the value of value1 is unchanged:
value1 = 1
value2 = 2
By having separate variables, each button click is operating on a different value. I would modify your code so there is only one value variable that both _Click functions modify.
Add this line:
textBox1.Text = (int.parseInt(textBox1.Text) + value2).toString();
after
value2 += 2;
into your button2_click method:
Related
Basically my question is how i add to a number like a calculator does for example? My code currently looks like this but it does a add operation instead of adding the number behind the existing number.
private void button1_Click(object sender, RoutedEventArgs e)
{
value1 = value1 + 1;
output = value1;
textresult.Text = output.ToString();
if the user presses the button twice it would be 2. I want it to be 11. How do i do this?
You should use string variable instead int variable
int a = 1;
int b = 1;
int c = a+b;
The result of c is 2
string a = "1";
string b = "1";
string c = a+b;
If you use string it will be "11"
I am beginner , am trying to create a calculator. the way of the code working is there is a method for summing and one for subtraction ETC.
when i call the subtraction method unwanted minus appears before the answer in the textbox ( i know my code could be using harder way to do the same purpose but i am just beginner trying to do some code )
double rat;
byte operations;
public void TheEqualMinus(double earlier) //Substraction Operation Method
{
double _minus;
_minus = Convert.ToDouble(result.Text);
double last = _minus - earlier;
result.Text = last.ToString();
}
private void button15_Click(object sender, EventArgs e)
{
//The Subtract Button
operations = 2;
rat = Convert.ToDouble(result.Text);
label1.Text = rat + " -";
result.Text = "";
}
private void button4_Click(object sender, EventArgs e)
{
// equal button
NewText = true; //boolean to newtext
switch (operations)
{
case (1): //addition
TheEqualSum(rat);
label1.Text = "";
break;
case (2): //substraction
TheEqualMinus(rat);
label1.Text = "";
break;
}
}
and the answer output becomes " - The Correct Answer i want "
ex. 9-6 = -3
so any ideas how to remove this minus ?
As per the comments above, this was fixed by simply changing this:
double last = _minus - earlier;
to this:
double last = earlier - _minus;
I am making a calculator to gain some experience with C#, atm i have one textbox ontop of one another, the lower one is called calculation; i want this one to show the sum being calculated. The text box on top is called result and i obviously want that to display the result; the result box works fine. I want the lower text box ( called calculation ) to display the + symbol which it wont let me do and at the moment i am only able to show the digits. I assume this is a data type problem. Any help/advice? thank you! (I'm sorting this out before moving onto the other symbols and eventually putting it into a switch case :) )
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
double num1 = 0;
double num2 = 0;
private void Clearbtn_Click(object sender, EventArgs e)
{
Calculation.Clear();
Result.Clear();
}
private void Numericclick(object sender, EventArgs e)
{
Button button = (Button)sender;
Calculation.Text = Calculation.Text + button.Text;
}
private void Plusbtn_Click(object sender, EventArgs e)
{
num1 = num1 + double.Parse(Calculation.Text);
Result.Show();
}
private void Equalsbtn_Click(object sender, EventArgs e)
{
num2 = num1 + double.Parse(Calculation.Text);
Result.Text = num2.ToString();
num1 = 0;
}
}
}
If you use the (+) operator with strings it concatenates them together.
This line Calculation.Text = Calculation.Text + button.Text;
In C# 6 will be this:
Calculation.Text = $"{Calculation.Text} + {button.Text}";
Lower than C# 6:
Calculation.Text = string.Format("{0} + {1}", Calculation.Text, button.Text);
String Concatenation Documentation: HERE
Example of difference between the operand + and as a string "+":
//+ operand concats string
var text = "abc";
var text2 = "def";
var result = text + text2;
//result -> "abcdef"
var result2 = text + "+" + text2;
//result -> "abc+def"
I have one textbox designated for "score" and another for "scores." Along with these two textboxes, I have a button called "add score." The score textbox handles 1 score. Every time I click the add score button, it should add a new score to the scores textbox. For example, if I enter "33" as the first score and click the add score button, then enter "45" and click the add score button, the scores textbox should display "33, 45." I want exactly 3 scores, and the 3 scores to display separately as a string in the scores textbox.
So far the only idea I had was to declare an array.
private void btnAddScore_Click(object sender, EventArgs e)
{
string name = txtName.Text;
int score = Convert.ToInt32(txtScore.Text);
int[] scores = new int[2];
}
You probably want to create your array before-hand so that it will be available for use when the button gets clicked. Instead of creating one inside to button handler.
With array you can use to show all the scores in the scores array as a string (comma separated):
string newString = string.empty;
foreach(int s in scores)
{
int n = 1, slen = scores.length;
if(n == 1 || n >= slen)
{ separator = ""; }
else
{ separator = ", ";}
newString = newString + separator + s.ToString();
n += 1;
}
Or static:
private void btnAddScore_Click(object sender, EventArgs e)
{
string name = txtName.Text;
if(Scores.length <= 3)
{
txtScores.Text = txtScores.Text.ToString() + ", " + txtScore.Text.ToString();
}
}
I will suggest you this approach:
private void btnAddScore_Click(object sender, EventArgs e)
{
string scores = txtName.Text;
if(!string.IsNullOrEmpty(scores) && scores.Split(',').Count() == 3)
{
MessageBox.Show("You can't enter more than three scores");
return;
}
if (string.IsNullOrEmpty(scores))
{
scores += txtScore.Text;
}
else
{
scores += ", " + txtScore.Text;
}
txtName.Text = scores;
}
I have two questions:
1) Is this the correct way to make my default value = 0 for variables, then pass a value given by the user into that variable?
protected void btnCheck_Click(object sender, EventArgs e)
{
lblYesNo.Text = "";
//default int values are set to 0
int remainder = 0;
int guess = 0;
remainder = int.Parse(txtRemainder.Text);
guess = int.Parse(txtAnswer.Text);
answer = (int)Session["answer"];
if (guess == answer)
{
lblYesNo.Text = lblYesNo.Text + "Correct!";
}
else
{
lblYesNo.Text = lblYesNo.Text + "Try Again..";
}
}//END Check Answer
2) how can I stop the Check_Click(submit button) from hiding the txtRemainder(textbox)? The reason it 'auto-hides' now is because I set the default value to 'txtRemainder.Visible = false;' in the Page_Load, which will make it hide unless the math problem is division. When I click on the btnDiv_Click(divide button) it resets it to 'txtRemainder.Visible = true;', because this provides a division question to be solved.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class BasicMath : System.Web.UI.Page
{
int number1;
int number2;
int answer;
protected void Page_Load(object sender, EventArgs e)
{
txtRemainder.Visible = false;
}
protected void GetRandom()
{
Random rand = new Random();
number1 = rand.Next(0, 10);
number2 = rand.Next(0, 10);
txtAnswer.Text = "";
txtRemainder.Text = "";
lblYesNo.Text = "";
}//END Get Random Number
protected void btnAdd_Click(object sender, EventArgs e)
{
GetRandom();
lblEquation.Text = number1.ToString() + " + " + number2.ToString();
answer = number1 + number2;
Session["answer"] = answer;
}//END Addition Button
protected void btnSub_Click(object sender, EventArgs e)
{
GetRandom();
if (number2 > number1)
{
answer = number2 - number1;
lblEquation.Text = number2.ToString() + " - " + number1.ToString();
}
else
{
answer = number1 - number2;
lblEquation.Text = number1.ToString() + " - " + number2.ToString();
}
Session["answer"] = answer;
}//END Subtraction Button
protected void btnMult_Click(object sender, EventArgs e)
{
GetRandom();
lblEquation.Text = number1.ToString() + " x " + number2.ToString();
answer = number1 * number2;
Session["answer"] = answer;
}//END Multiplication Button
protected void btnDiv_Click(object sender, EventArgs e)
{
Random rand = new Random();
number1 = rand.Next(1, 10);
number2 = rand.Next(1, 10);
/*will only display the txtRemainder(textbox) while using the Divide button,
txtRemainder will auto-hide when using another button because
it's default setting of '.Visible = false' is placed in the Page_Load*/
txtRemainder.Visible = true;
lblEquation.Text = number1.ToString() + " / " + number2.ToString();
answer = number1 / number2;
Session["answer"] = answer;
}//END Division Button
protected void btnCheck_Click(object sender, EventArgs e)
{
lblYesNo.Text = "";
//default int values are set to 0
int remainder = 0;
int guess = 0;
remainder = int.Parse(txtRemainder.Text);
guess = int.Parse(txtAnswer.Text);
answer = (int)Session["answer"];
if (guess == answer)
{
lblYesNo.Text = lblYesNo.Text + "Correct!";
}
else
{
lblYesNo.Text = lblYesNo.Text + "Try Again..";
}
}//END Check Answer
}
If this question doesn't make sense please ask for clarification.
Question 1:
Yes, that is the correct way to initialize your variables to default values of zero, although int variables are initialized to zero by default, so even if you omitted the assignment, they would still default to zero.
The method you're using to accept the user input is correct, but could throw an exception if the values entered by the user are not Int32 values (think 3.2). As it stands, you have no try..catch blocks to deal with these exceptions. You could either add these try..catch blocks, or you could use the TryParse() method to check that the values are valid. For example:
protected void btnCheck_Click(object sender, EventArgs e)
{
lblYesNo.Text = "";
//default int values are set to 0
int remainder = 0;
int guess = 0;
if (!Int32.TryParse(txtRemainder.Text, out remainder))
{
// do something here to inform the user that remainder is invalid
return;
}
if (!Int32.TryParse(txtAnswer.Text, out remainder))
{
// do something here to inform the user that answer is invalid
return;
}
answer = (int)Session["answer"];
if (guess > answer)
{
lblYesNo.Text = lblYesNo.Text + "Try Again..";
}
else if (guess < answer)
{
lblYesNo.Text = lblYesNo.Text + "Try Again..";
}
else
{
lblYesNo.Text = lblYesNo.Text + "Correct!";
}
}//END Check Answer
TryParse() will convert the value into the output variable if it's a valid value & return true to indicate success, otherwise it will return false if it was not able to perform the conversion.
Question 2:
In order to hide txtRemainder when the page first loads & then to keep it hidden if any button was clicked other than btnDiv, here is a proposed solution. First, the code:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack) {
lblTest.Visible = false;
} else {
foreach (string ctrl in Request.Form) {
Control c = FindControl(ctrl);
if (c is Button) {
txtRemainder.Visible = c.ID == "btnDiv";
return;
}
}
}
}
Now for some explaining. When the page initially loads, the label is hidden (by the !IsPostBack check). If the request is indeed a postback, we go through the collection of returned form controls (contained in the Request.Form collection) & check to see if a button is present that could have caused the postback. Buttons are rendered in the HTML as <input type="submit" .. /> elements, and upon postback, only the button that was clicked is sent back in the Form collection, even if there are multiple submits on the page. A more detailed explanation can be found here
Now, if a button did indeed cause the postback, then we check to see if this button was btnDiv. If it was, the comparison returns true & txtRemainder is displayed. If not, it is hidden.
This way, there is no need to show or hide txtRemainder in each event handlers. You wouldn't even need to set it to visible in the event handler for btnDiv.
EDIT
Based on the requirement listed in the comments, I've altered my answer to question 2 so as to provide an alternative method to having to show or hide the label in each button event.
Question1:
If you are using .Net 4.0 and up, consider using the TryParse method, and check the result for success, this way you have better control over parsing values and trapping exceptions
e.g.
int number = 0;
bool result = false;
result = int.TryParse("123", out number);
if (!result)
{
throw new InvalidCastException("Error converting number");
}
Question2:
It looks like you're using Asp.Net, so try testing for Page.IsPostBack in your Page_Load event, this way you can determine whether the page loads because of an initial load, or because you sent data to the server i.e. clicked a button.
Hope this helps!