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Input string was not in a correct format. Textchange problem [duplicate]

This question already has answers here:
Input string was not in a correct format
(9 answers)
Closed 3 years ago.
C# CODE
I have a problem with my "Check in" form.
I want to multiply the txtsubtotal and txtadvancepayment.
In textchange if I put number on the txtadvancepayment, the overallresult is correct. But if I clear the txtadvancepayment (Incase when the user puts a wrong value) it would be error. The error says "Input string was not in a correct format."
What should I do?
My Code downward
int overalltotal = 0;
int a = Convert.ToInt32(txtsubtotal.Text);
int b = Convert.ToInt32(txtadvancepayment.Text);
overalltotal = a - b;
txttotalbalance.Text = overalltotal.ToString();

An empty string cannot be parsed as an int. As others have mentioned, you can use int.TryParse which accepts a string as the first parameter and an out int as the second parameter, which holds the parsed value. You could do this:
int overallTotal = 0;
int a = 0;
int b = 0;
// TryParse returns a bool
// If either of these fails, the variable a or b will keep the default 0 value
int.TryParse(txtSubtotal.Text, out a);
int.TryParse(txtAdvancePayment.Text, out b);
// Sum a and b
overallTotal = a + b;
If you want to show an error to the user that one or both fields isn't a valid integer, you can assign a bool variable such as var aIsNumber = int.TryParse(...) and then check if aIsNumber or bIsNumber is false. If so, then a and/or b could not be parsed to an int.

You could use Int32.TryParse.
Int32.Parse attempts to convert the string representation of a number to its 32-bit signed integer equivalent and returns value indicates whether the operation succeeded. This would mean, in case your textbox is empty or contains a invalid numeric representation, and the method would return false since it would not be able to convert it to int32
For example
if(Int32.TryParse(txtsubtotal.Text,out var a)
&& Int32.TryParse(txtadvancepayment.Text,out var b))
{
// Code which requires a and b
}

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());

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.

convert variable in asp.net

I wrote a piece of simple code that I dont to find what the problem.
the code is:
var sortSecurities="SELECT * FROM securities";
int total=0;
var value="";
foreach(var row in db.Query(sortSecurities))
{
value=row.lastGate;
total=Convert.ToInt32(value)*100;// here the problem with compilation..
db.Execute("INSERT INTO holding(IDgrossPortfolio,IDSecurity,totalHolding,units,buyGate) "+"VALUES (#0,#1,#2,#3,#4)",row.category,row.number,total,"100",row.lastGate);
}
what the problem with the convert?
the error is:
Exception Details: System.FormatException: Input string was not in a correct format.

value does not hold a value that can be converted to Int32. If you could do some debugging and see what the value of it is from row.lastGate, you might see what the problem is.
Also, not sure what is returned by db.Query(sortSecurities) (or really what kind of object row.lastGate is), but you can also try to change value=row.lastGate; to value=row.lastGate.ToString();

you can use try parse to check if the value actually contains a number
int total;
bool result = Int32.TryParse(value, out total);
if (result)
{
db.Execute("INSERT INTO holding(IDgrossPortfolio,IDSecurity,totalHolding,units,buyGate) "+"VALUES (#0,#1,#2,#3,#4)",row.category,row.number,total,"100",row.lastGate);
}

Your value isn't successfully being parsed by Convert.ToInt32()
Alternatively, consider using Int32.TryParse() and validate if the data is indeed the type of data you're expecting.
int result;
if(Int32.TryParse(row.lastGate, out result))
{
//row.lastGate was a valid int
total = result * 100;
}
else
{
//row.lastGate wasn't a valid int
}

Thanks you for all... I try now and found elegant answer.
Like I wrote in the comments, becouse I know that the value of row.lastGate
represent a number I don't need to check it.
So I try this and it works:
var sortSecurities="SELECT * FROM securities";
int total=0;
double value=0;
foreach(var row in db.Query(sortSecurities))
{
value=Convert.ToDouble(row.lastGate);
total=Convert.ToInt32(value)*100;//100 is default
db.Execute("INSERT INTO holding(IDgrossPortfolio,IDSecurity,totalHolding,units,buyGate) "+"VALUES (#0,#1,#2,#3,#4)",row.category,row.number,total,"100",row.lastGate);
}
Probably I needed to change the value first of all to double and then to int
Becouse when I try to change it directly to int the Compiler did'nt interpret the
string right, becouse of the dot in the number (type double).
thanks about the the intention..