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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
}

Having trouble casting string to integer

I'm trying to convert the string "127.0" to an integer.
I tried this function:
int getInt(string numStr)
{
int result;
int.TryParse(numStr, out result);
return result;
}
But when I call it as int x = getInt("127.0"); then int.TryParse() sets result to 0.
When I rewrite the function like this:
int getInt(string numStr)
{
result=Convert.ToInt32(numStr);
return result;
}
the same getInt() call throws this exception:
Input string was not in a correct format.

The issue here is that "127.0" is not an integer, it's a floating point number. You will need to parse it using one of the other floating point types (i.e. double, float, Decimal, etc.).
You may want to consider either stripping off any values after the decimal point and attempting to parse it, or parsing it as another type and casting it as an integer :
int result = (int)Convert.ToDouble("1.270");
You could also take advantage of the Math.Truncate() function which would give you the integer portion of your value :
int result = (int)Math.Truncate(Convert.ToDouble("127.0"));

First off, you need to check the return value of int.TryParse(). If it returns false, then the string could not be converted.
Had you done that, you would see it returned false because 127.0 does not describe an integer value (it describes a floating point value).
Note that decimal.TryParse() would succeed here. You need to figure out if you need an integer or floating point value, and reject data that is incorrect.

An int cannot contain a decimal point; that makes it either a double, a float, or a decimal. Try to pull the number minus anything from the decimal point over to the right, like this:
int getInt(string numStr)
{
int result;
string[] splitup;
string number;
if (numstr.Contains('.'))
{
splitup = numstr.Split('.');
number = splitup[0];
int.TryParse(number, out result);
}
else
{
int.TryParse(numstr, out result);
}
return result;
}

Rion Williams is absolutely correct, IMHO.
Along with the fact that what you are parsing is not an integer, I'd personally use the TryParse method. Many of the .NET types have it, and it's quite a bit "safer" (it won't throw exceptions) than just parsing a string.
Example:
string stringValue = "127.0";
int intValue;
if(Int32.TryParse(stringValue, out intValue))
{
// return value
}
// handle the failure
If you don't like that, I'd wrap it in a try-catch...

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..

Convert System.Web.UI.WebControls.Unit to int in c#

How can I convert from an ASP.NET Unit structure to int in c#? Or reverse?

The Unit type has a Value property. This is a double, but you can cast it to an int if you want. The casting may cause a loss of precision, but you are probably aware of that.
To create a Unit just use the constructor that takes an int.

If you mean the Unit class:
The Unit class can represent values
only between -32768 and 32767.
But it depends if you want the Pixel or Percentage value.
myUnit.Value will get the value as pointed out.
Use the constructor public Unit(int value) to convert back.
If you mean a uint: there's 2 possible obvious ways:
int n = Convert.ToInt32(myUint);
int n = (int)myUint;

For ASP.NET Unit:
unit.IsEmpty ? 0 : Convert.ToInt32(unit.Value);

Use Unit.Value property. It will return double and you can cast it to int
Something like (int)xyz.Value
WEhere xyz is the unit variable
To convert int to unit use new Unit(value)

Probably he need this:
int myInt = 1;
uint myUint = (uint)myInt;
uint myUint = 1;
int myInt = (int)myUint;

The Value property returns a dobule, that you can convert to an integer:
int h = (int)someControl.Height.Value;
However, the conversion might not make sense for some unit types. If you don't know for certain that the unit is of a specific type, you would want to check the Type property first.

Convert.Toint32( UInt );
I guess u meant UInt not Unit
EDIT : Ok thought you meant uint sorry