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I can't convert string to int

i was making a visual studio program that automatically solve some kind of math problems. then i keep failing to convert text from textbox in window form. so i tried every way i found in google to convert string to int but still don't work. so i was looking for solution here but i could't know why this is broken
three textbox is named coefficient_of_absolute, x_coefficient, constant.
and this is part of my code that supposed to convert text of textbox to number
MessageBox.Show(coefficient_of_absolute.Text);
MessageBox.Show(coefficient_of_absolute.Text.GetType().ToString());
int coa_int = Convert.ToInt32(coefficient_of_absolute.Text);
one messagebox showed that text is 1 and the other showed that type of the text is string
but this program say that Input string is malformed
this text is satan. it stole more than 10hours of my life. please help me
edit)
MessageBox.Show(coefficient_of_absolute.Text);
MessageBox.Show(coefficient_of_absolute.Text.GetType().ToString());
int coa_int = int.Parse(coefficient_of_absolute.Text);
it didn't work
MessageBox.Show(coefficient_of_absolute.Text);
MessageBox.Show(coefficient_of_absolute.Text.GetType().ToString());
int output;
int.TryParse(coefficient_of_absolute.Text, out output);
MessageBox.Show(output.ToString());
this made num to zero whatever it is
enter image description here
MessageBox.Show(coefficient_of_absolute.Text.Length.ToString());
cheaking around text revealed length of the text is 1, which means there was nothing around it

you can try TryParse instead of Convert.ToInt32 , that way you can check if you catch exception.
int outputNumber;
bool res = int.TryParse(text1, out outputNumber);
if (res == false)
{
// String is not a number.
}

string textBoxString = textBox1.Text.ToString();
int textBoxInt = int.Parse(textBoxString);
int test = textBoxInt + 1;
string testText = test.ToString();
MessageBox.Show(testText);
converting the variable into string first then converting into int solved this problem

Parsing the value of an integer using a string?

I have Script2 which has int restaurant1Current, along with several other variables with similar names. On another script, I'm trying to parse the value of restaurant1Current using this code. category is a string with the value of "restaurant1".
string currentStringBuffer = "Script2." + category + "Current";
int currentNumber = int.Parse(currentStringBuffer);
I want to be able to use the same code as I change the value of category hence the need to parse it using a string instead of referencing the variable directly. Is this the correct syntax or am I missing something? As is the code tells me "The input string is not in the correct format" but when debugging it shows that the string contains the value "Script2.restaurant1Current" which again is an int. So why wouldn't I be able to parse the value to currentNumber in the next line?

public Enum Categories{
Restauraunt,
Grocer,
Bank
}
Enum stands for enumeration, it is a numbered list. with this particular enum,
Categories.Bank =2; so you can call or assign.
something.category=2;
or
int rando = Categories.Bank

Formatting values

Hi i have a int example as 3 i need to format it as 003 . is the only way is convert to a string and concat and convert back ?

I guess this is what you want:
int n = 3;
string formatted = n.ToString("000");
Alternatively:
string formatted = String.Format("{0:000}", n);
More info here.

You can apply the .ToString("000"); method.

Debug.WriteLine(3.ToString("000"));
You can parse the resulting string value by using int.Parse or int.TryParse:
Debug.WriteLine(int.Parse("003"));
See Custom Numeric Format Strings

If it's an int object, the leading zeros will always be removed, regardless if you convert it to a string and back.

use the pad functionint i = 1;
i.ToString().PadLeft(3, '0');

How to convert textbox.text into int or what to use for int only input instead?

How do I convert a TextBox to int or is there a box inside WPF that supports only numbers?

To convert string to int you can use, Parse:
string text = "1234";
int value = int.Parse(text);
Or you could use NumericUpDown control.

If you only want numeric input, you might be better off with numbericupdown. Of course, you could just validate the input using tryparse...

String.Format in C# not returning modified int value

I am tring to return an int value with comma seperators within the value.
12345 would be returned as 12,345
The follwing code works:
int myInt = 1234567;
MessageBox.Show(string.Format("My number is {0}", myInt.ToString("#,#")));
12,345 is displayed as expected.
While the following code does no work, but from what I am reading, should work:
int myInt = 1234567;
MessageBox.Show(string.Format("My number is {0:#,#}", myInt.ToString()));
12345 is displayed.
Can you help me understand why the second set of code is not working?
Thanks

You shouldn't ToString the int before the format. Try this:
MessageBox.Show(string.Format("My number is {0:#,#}", myInt));

You are converting to string before the formatter has the chance to apply the formatting. You are looking for
MessageBox.Show(string.Format("My number is {0:#,#}", myInt));

myInt.ToString() is redundant since you are using a String.Format(). The point of String.Format is to supply is with a bunch of objects and it will create a string for you. No need to convert it to a string.
In order for the Numeric Format to reflect you need to give it an actual numeric value type not a numeric value that's of type string.
When you give the Format method a string it doesn't take into account any numeric formatting since its already a string type.
int myInt = 1234567;
MessageBox.Show(string.Format("My number is {0:#,#}", myInt));

When you use format strings "inline" as in your second example, the input to the parameter needs to be the original value (i.e int, double, or whatever) so that the format string can do something useful with it.
So omitting the ToString from the second call will do what you want:
int myInt = 1234567;
MessageBox.Show(string.Format("My number is {0:#,#}", myInt));