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Subtracting int from double leads to an error

I have an int and a double, but as soon as I try to subtract the integer from the double, the following error is thrown:
Input string was not in a correct format.
Now lets look at the code:
double TotalNoRegis = values.Sum(); // This is a LIST and its = 1569
string otherFe ="600";
double totalafter;
if(otherFe != string.Empty || otherFe!= "") // This part works fine
{
totalafter = TotalNoRegis - Convert.ToInt32(otherFe); // Here the error is thrown
}
What am I doing wrong here? I looked at this Example, which is basically the same thing: int x = 1 and int y = 2 and then int this = x-y;
Please let me know if you know the issue here.

What am I doing wrong here?
Lots.
if(otherFe != string.Empty || otherFe!= "") // This part works fine
That's nonsensical code. string.Empty and "" are the same string.
Instead use
if (!string.IsNullOrEmpty(otherFe))
Moving on:
totalafter = TotalNoRegis - Convert.ToInt32(otherFe); // Here the error is thrown
You claim that the error is the subtraction, but it is not. The problem is in the ToInt32. You are passing some other string than the one you are showing.
The way I like to do this is by making an extension method:
static public class Extensions
{
public static int? ParseAsInteger(this string s) {
if (string.IsNullOrEmpty(s)) return null;
int i;
return int.TryParse(s, out i) ? (int?)i : (int?)null;
}
// Similarly write `ParseAsDouble` and so on.
}
Now you have an extension you can use:
double? totalAfter = TotalNoRegis - otherFe.ParseAsInteger();
(Or ParseAsDouble, or whatever.)
If otherFe was valid, then totalAfter has the total; if it was not, then it is null.
The lesson here is: move the type conversion logic into its own method which you can independently test. Then the logic at the call site of that method becomes simpler and easier to follow.

You should use an integer instead of a double, especially if you don't have a reason to use the double. So to rectify, you could simply do the following.
int total = values.Sum();
var other = "6000";
if(!string.IsNullOrEmpty(other))
if(int.TryParse(other, out int subtractor))
total -= subtractor;
If you require a double, then use but if you don't why bother? Also, you are subtracting fifteen hundred items from six thousand, your total after will always be negative or often be negative. Is that your desired intent?
Something to note, with the TryParse if it fails it'll skip the subtraction rather than fail like parse or convert would do. Also do you want the sum of the list or count?

convert string to int error in c#

Hello I am trying to convert String to Integer.
The code below shows a part from where I am trying to convert my string to integer.
if (other.gameObject.CompareTag("PickUp"))
{
if ( checkpointboolean == false)
{
string pickupName = other.ToString(); //other = Pickup4
//Remove first 6 letters thus remaining with '4'
string y = pickupName.Substring(6);
print(y); // 4 is being printed
int x = 0;
int.TryParse(y, out x);
print (x); // 0 is being printed
I also tried the below code and instead of '0' I am getting the following error:
if (other.gameObject.CompareTag("PickUp"))
{
if ( checkpointboolean == false)
{
//Get Object name ex: Pickup4
string pickupName = other.ToString();
//Remove first 6 letters thus remaining with '4'
string y = pickupName.Substring(6);
print(y);
int x = int.Parse(y);
FormatException: Input string was not in the correct format
System.Int32.Parse (System.String s)

int.TryParse returns a boolean, true if it succeeded and false if not. You need to wrap this in a if block and do something with that logic.
if(int.TryParse(y, out x))
print (x); // y was able to be converted to an int
else
// inform the caller that y was not numeric, your conversion to number failed
As far as why your number is not converted I could not say until you post what the string value is.

Your first attempt is the best for this case, that code works fine, The int.TryParse() giving 0 to the out parameter and returns false means the conversion is failed. The input string is not in the correct format/ it cannot be converted to an integer. You can check this by using the return value of the int.TryParse(). For this what you need to do is :-
if(int.TryParse(y, out x))
print (x); //
else
print ("Invalid input - Conversion failed");

First of all, ToString() usually uses for debug purpose so there's no guarantee that
other.ToString()
will return the expected "Pickup4" in the next version of the software. You, probably, want something like
int x = other.gameObject.SomeProperty;
int x = other.SomeOtherProperty;
int x = other.ComputePickUp();
...
If you, however, insist on .ToString() you'd rather not hardcode six letters (the reason is the same: debug information tends to change from version to version), but use regular expressions or something:
var match = Regex.Match(other.ToString(), "-?[0-9]+");
if (match.Success) {
int value;
if (int.TryParse(match.Value, out value))
print(value);
else
print(match.Value + " is not an integer value");
}
else
print("Unexpected value: " + other.ToString());

How to convert textbox value to integer

I have some textboxes in my C# windows form application. I want to do the following:
inRed = Convert.ToInt32(tbRed.Text.ToString().Length < 0 ? tbRed.Text = "0" : tbRed.Text);
inGreen = Convert.ToInt32(tbGreen.Text.ToString().Length < 0 ? tbGreen.Text = "0" : tbGreen.Text);
inBlue = Convert.ToInt32(tbBlue.Text.ToString().Length < 0 ? tbBlue.Text = "0" : tbBlue.Text);
inCyan = Convert.ToInt32(tbCyan.Text.ToString().Length < 0 ? tbCyan.Text = "0" : tbCyan.Text);
inMagenta = Convert.ToInt32(tbMagenta.Text.ToString().Length < 0 ? tbMagenta.Text = "0" : tbMagenta.Text);
If the textbox doesn't have a value, enter a 0 and convert to integer, otherwise convert the value of the textbox to integer.
I am getting the following error for inCyan, where the textbox is empty:
Input string was not in a correct format.
How can I achieve what I am looking for?

Instead of Convert.ToInt32, use Int32.TryParse. This gives you feedback regarding if it was a valid integer. e.g.
String textboxValue = "1";
Int32 i;
if (!String.IsNullOrWhitespace(textboxValue) && // Not empty
Int32.TryParse(textboxValue, out i)) { // Valid integer
// The textbox had a valid integer. i=1
} else {
// The texbox had a bogus value. i=default(Int32)=0
// You can also specify a different fallback value here.
}
As a follow-up, String.IsNullOrWhitespace makes it easy to decipher if a value is supplied, but (depending on your .NET version) is may not be available (and you may only have String.IsNullOrEmpty.
If need be, the polyfill is something long the lines of:
Boolean SringIsNullOrWhitespace(String input)
{
return !String.IsNullOrEmpty(input) && input.Trim().Length > 0;
}
Also, if you find yourself trying to perform this parsing frequently, you could refactor it into a helper class:
public static class ConvertUtil
{
public Int32 ToInt32(this String value)
{
return ToInt32(value, default(Int32));
}
public Int32 ToInt32(this String value, Int32 defaultValue)
{
#if NET4
if (!String.IsNullOrWhiteSpace(value))
#else
if (!String.IsNullOrEmpty(value) && value.Trim().Length > 0)
#endif
{
Int32 i;
if (Int32.TryParse(value, out i))
{
return i;
}
}
return defaultValue;
}
}
// explicit
inRed = ConvertUtil.ToInt32(tbRed.Text, 0/* defaultValue*/);
// As extension
inRed = tbRed.Text.ToInt32(0/* defaultValue*/);

You can do something like
// Initialise variable with 0
int value;
// Try parse it, if it's successful and able to parse then value is set to the int equivalent of your text input
int.TryParse(inputVariable, out value);
return value
This is a simple way of dealing with your problem - note, if the parse fails then it returns 0 to value.
How you would apply it to your particular problem.
int inMagenta;
int.TryParse(tbMagenta, out inMagenta);
etc.....

You can use tryparse.
int inRed; //default value will be 0 , if the string is not in a valid form
Int32.TryParse(tbRed.Text.ToString(), out inRed);

Convert a string to integer in C#/.NET [duplicate]

This question already has answers here:
How to convert string to integer in C#
(12 answers)
Closed 8 years ago.
I need to convert a string to integer. My string can be of any type (float/int/string/special character).
For example:
If my string is "2.3", I need to convert to = 2
If my string is "anyCharacter", I need to convert to = 0
If my string is "2", I need to convert to = 2
I tried the following:
string a = "1.25";int b = Convert.ToInt32(a);
I got the error:
Input string was not in a correct format
How do I convert it?

Use Double.TryParse() and once you get the value from it, convert it to int using Convert.ToInt():
double parsedNum;
if (Double.TryParse(YourString, out parsedNum) {
newInt = Convert.ToInt32(num);
}
else {
newInt = 0;
}

Try to parse it as a floating point number, and convert to integer after that:
double num;
if (Double.TryParse(a, out num) {
b = (int)num;
} else {
b = 0;
}

This should help: treat any string as if it were a double, then Math.Floor() it to round it down to the nearest integer.
double theNum = 0;
string theString = "whatever"; // "2.3"; // "2";
if(double.TryParse(theString, out theNum) == false) theNum = 0;
//finally, cut the decimal part
int finalNum = (int)Math.Floor(theNum);
NOTE: the if might not be needed per-se, due to theNum initialization, but it's more readable this way.

I think Convert.ToInt32 is the wrong place to look for - I would use Integer.Tryparse and if TryParse evaluates to false, assign a 0 to the variable. Before the TryParse, you could simply delete any character after the dot, if you find it in the string.
Also, keep in mind that some languages use "," as a separator.

Try:
if (int.TryParse(string, out int)) {
variable = int.Parse(string);
}

As far as I know, there isn't any generic conversion, so you'd have to do a switch to find out the type of the variable and then use either of the following (for each type):
int.Parse(string)
or
int.TryParse(string, out int)
The second one will return a boolean which you can use to see if the conversion passed or failed.
Your best option would be to use double or decimal parsing as this won't remove any decimal places, unlike int.

bool Int32.TryParse(string, out int)
The boolean return value indicates if the conversion was successful or not.

Try something like this:
public int ForceToInt(string input)
{
int value; //Default is zero
int.TryParse(str, out value);
return value;
}
This will do the trick. However I don't recommend taking this approach. It is better to control your input whereever you get it.

Is there a TryInt() conversion for String values?

I want to convert a value entered in a textBox (which can only be empty or "1" or "2" or "3") to an integer. If empty I want it to be 0, otherwise, it's corresponding value (1, 2, or 3).
Is there a way to do that like:
MyIntVal = TryConvertToInt(textBox1.Text, 0);
...where an empty string or anything not readily convertible to an int would default to 0?

You can use the Int32.TryParse Method:
int myIntVal;
if (!int.TryParse(textBox1.Text, out myIntVal))
{
myIntVal = 42;
}
If the method returns false, the text could not be parsed. myIntVal will be 0 in this case; you can assign a different default value to your variable as shown above.

int result = 0;
int.TryParse(stringValue, out result);
Will default to 0 if stringValue cannot be parsed to an int.
http://msdn.microsoft.com/en-us/library/f02979c7.aspx

There's the static TryParse. It returns true if it works.
int myIntVal;
int.TryParse(textBox1.Text, out myIntVal);