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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

Trying to understand strange string concatenation behavior

I have a very simple method that takes a string, breaks it into a char array, then creates a new string from the pieces. However it is performing unexpectedly and I don't understand why? Here is a picture of breakpoint. The input string in this case is "20160622".
Edit: Sorry for the pic. Here is the question in text.
internal class Program
{
private static void Main()
{
string test = "20160622";
Console.WriteLine(ConvertDateField(test));
Console.ReadKey();
}
private static string ConvertDateField(string date)
{
var temp = date.ToCharArray();
var output = temp[0] + temp[1] + temp[2] + temp[3] + "-" + temp[4] + temp[5] + "-" + temp[6] + temp[7] + " 00:00:00";
return output;
}
}
The output is "201-06-22 00:00:00".
Edit 2: I understand there are probably better ways to do this. What I am trying to understand is why this code is functioning the way it is. ie. why is the 6 the only char not being concatenated?
As you can see, the fourth char, temp[3] which is a '6', is not being concatenated into the output string. Why?
Edit 3: I solved the problem this way
private static string ConvertDateField(string date)
{
return DateTime.ParseExact(date, "yyyyMMdd", CultureInfo.InvariantCulture).ToString("yyyy-MM-dd 00:00:00");
}
Thank you Steve for your advice.

For your question. The char concat is not a string concat. What happened is that c# is doing Math operation for the chars by casting them to int with ASCII.
The corresponding ascii for temp 1, 2, 3, 4 are 50, 48, 49, 54 which the sum is 201. (what a coincidence)
and then int + string concat resulted in string so the rest of the string worked as expected.
There is an easier way to perform the convert if it was a DateTime object. You can simply call dateTime.ToString("yyyy-MM-dd 00:00:00") and you will get the result you want.

ulong.Parse(string, NumberStyles) Exception C#

i been working on this "string to Binary" method for longer than usual and i have no idea where i m going wrong.
i have already searched the internet for solution but nothing seem to be working the way it supposed to do.
public static string hexToBin(string strValue)
{
byte[] hexThis = ASCIIEncoding.ASCII.GetBytes(strValue.ToString());
string thiI = ToHex(strValue);
ulong number = UInt64.Parse(*string*, System.Globalization.NumberStyles.HexNumber);
byte[] bytes = BitConverter.GetBytes(number);
string binaryString = string.Empty;
foreach (byte singleByte in bytes)
{
binaryString += Convert.ToString(singleByte, 2);
}
return binaryString;
}
ToHex(string) takes string and returns its hex representation.
but all i keep getting is "Input string was not in a correct format." at the ulong.Parse(string, NumberStyle); and no matter what are my inputs i keep getting the "FormatException" "Input string was not in a correct format." Error.
the inputs and its outputs
string: format exception - "Hello"
hex: format exception - "48 65 6C 6C 6F"
byte[]: format exception - { 72, 101, 108, 108, 111 }
i have also tried using the "Hello" string, but it threw me the same error.
would you please let me know what i m doing wrong in here?
i also have tried "Clean/build/rebuild" restart visual studio, but i keep getting the same format exception.
EDIT,, used UInt64.Parse() not ulong.Parse() and the used string is "Hello" w/o quotation.
EDIT #2,,
so i did this based on knittl suggestion and used the Convert.ToUInt64 instead of the parse, but still getting same error
ulong binary;
string binThis;
byte[] ByteThis;
binThis = "Hello";
ByteThis = ASCIIEncoding.ASCII.GetBytes(binThis);
binary = Convert.ToUInt64(ByteThis);
Console.WriteLine(binary);
the CurrentCulture is set to en-US and i m also using en-US keyboard
EDIT #3 - Solved
thanks to knittl
the solution is as follow:
string thestring = "example";
string[] finale = new string[thestring.Length];
foreach (var c in ByteThis)
{
for (int i = 0; i < ByteThis.Length; i++)
{
thestring = Convert.ToString(c, 2);
thestring = "0" + thestring;
if (thestring.Length == 9)
thestring.Remove(0, 1);
finale[i] = thestring;
Console.WriteLine(finale[i]);
}
}
the final for is to check on the solution.
this question aimed to get the binary representation of a given string.

Not totally clear, what your method should do (i.e. what format the input string is. Is it a bas10 number, or already a hexadecimal number?)
If it's a hexadecimal number, use ulong.Parse(inputStr, NumberStyles.HexNumber). If not, simply use ulong.Parse(inputStr). Note that NumberStyles.HexNumber does not allow the 0x prefix (Convert.ToUInt64(inputStr) does however).
Then, once you have your input string parsed to a number, simply use Convert.ToString(number, 2) to convert to base2. You will notice that there is no overload which takes an ulong and an int, but you can simply cast your number to a (signed) long, since the binary representation will be identical between the two (cf. two's complement). So, in effect Convert.ToString((long)number, 2).
No need for complicated loops and conversions to byte arrays.

Bonus answer.
If you are not too concerned with performance, you can even use a LINQ one-liner:
Encoding.ASCII.GetBytes(inputStr).Aggregate(
new StringBuilder(),
(sb, ch) => sb.Append(Convert.ToString(ch, 2).PadLeft(8, '0')),
sb => sb.ToString());

Convert hexadecimal string to an integer

int value = Convert.ToInt32('o');
Byte[] b = new Byte[] { ( byte)value };
File.WriteAllBytes(Default.ProjectsPath , b);
when I open the file it displays o, I want to write the byte value to the file?

Remove the0x then convert:
int i = Convert.ToInt32("0xFE".Substring(2), 16);

Convert.ToInt16(string) will not be able to convert strings that start with '0x', even though that's the correct notation for base 16 numbers. If you want to use your solution, you will need to remove the "0x" from the string conversion. Replace
string s=String.Format("0x{0:X}", value);
with
string s=String.Format("{0:x}", value);
Or you can use Alex K.'s idea and replace
int x=Convert.ToInt16(s);
with
int x=Convert.ToInt16(s.Substring(2));

if you are the one producing the string in the first place then like Alex Barac suggested, dont place a 0x prefix at all... (why create problems you dont need)
if you have to have the prefix, use it... if the prefix is '0x' use
int i = Convert.ToInt32("0xFE".Substring(2), 16); as Alex K. suggested
if it is not '0x', then it probobally a Base10 number:
int i = Convert.ToInt32("342", 10);

C# - Input string was not in a correct format

I am working on a simple windows forms application that the user enters a string with delimiters and I parse the string and only get the variables out of the string.
So for example if the user enters:
2X + 5Y + z^3
I extract the values 2,5 and 3 from the "equation" and simply add them together.
This is how I get the integer values from a string.
int thirdValue
string temp;
temp = Regex.Match(variables[3], #"\d+").Value
thirdValue = int.Parse(temp);
variables is just an array of strings I use to store strings after parsing.
However, I get the following error when I run the application:
Input string was not in a correct format

Why i everyone moaning about this question and marking it down? it's incredibly easy to explain what is happening and the questioner was right to say it as he did. There is nothing wrong whatsoever.
Regex.Match(variables[3], #"\d+").Value
throws a Input string was not in a correct format.. FormatException if the string (here it's variables[3]) doesn't contain any numbers. It also does it if it can't access variables[3] within the memory stack of an Array when running as a service. I SUSPECT THIS IS A BUG The error is that the .Value is empty and the .Match failed.
Now quite honestly this is a feature masquerading as a bug if you ask me, but it's meant to be a design feature. The right way (IMHO) to have done this method would be to return a blank string. But they don't they throw a FormatException. Go figure. It is for this reason you were advised by astef to not even bother with Regex because it throws exceptions and is confusing. But he got marked down too!
The way round it is to use this simple additional method they also made
if (Regex.IsMatch(variables[3], #"\d+")){
temp = Regex.Match(variables[3], #"\d+").Value
}
If this still doesn't work for you you cannot use Regex for this. I have seen in a c# service that this doesn't work and throws incorrect errors. So I had to stop using Regex

I prefer simple and lightweight solutions without Regex:
static class Program
{
static void Main()
{
Console.WriteLine("2X + 65Y + z^3".GetNumbersFromString().Sum());
Console.ReadLine();
}
static IEnumerable<int> GetNumbersFromString(this string input)
{
StringBuilder number = new StringBuilder();
foreach (char ch in input)
{
if (char.IsDigit(ch))
number.Append(ch);
else if (number.Length > 0)
{
yield return int.Parse(number.ToString());
number.Clear();
}
}
yield return int.Parse(number.ToString());
}
}

you can change the string to char array and check if its a digit and count them up.
string temp = textBox1.Text;
char[] arra = temp.ToCharArray();
int total = 0;
foreach (char t in arra)
{
if (char.IsDigit(t))
{
total += int.Parse(t + "");
}
}
textBox1.Text = total.ToString();

This should solve your problem:
string temp;
temp = Regex.Matches(textBox1.Text, #"\d+", RegexOptions.IgnoreCase)[2].Value;
int thirdValue = int.Parse(temp);