Convert.ToDouble() throws Format Exception

Question

I am reading Data from an internal Database. The code assigns value read from the database to double.

if (Convert.ToDouble(PricefromString) == Price && PriceFound == false)

PricefromString has been read from the database.

Most of the time the code works fine, but i get a FormatException, when the string value is an integer value. In this particular case, when PricefromString = 77, i get the format exception. I tried debugging and checked the input string to ToDouble() which is throwing the exception.

Edit: PricefromString has a whitespace tab character at the end attached. It works perfectly fine when the string is a double value eg. 76.99, 77.01, but i get an FormatException error when price reaches an integer value.

Any leads ?

You Can Use Double.TryParse(value, out number) for preventing from getting exception. — dev-masih, Nov 06 '14 at 04:30
Thanks, it fixed it. May I know why I was getting the error from using convert.ToDouble() ? — novice, Nov 06 '14 at 04:33

score 2 · Answer 1 · edited May 23 '17 at 10:25

2

There might be something else, because if 77 is of String data type then definitely it will work.
Check to see if it does not contain any other characters like currency symbols.

Double.Parse or Convert.ToDouble will throw an exception if it cannot parse the given value.

Whereas Double.TryParse returns a bool indicating whether it succeeded.

Try this:

double value;
Double.TryParse(PricefromString, out value);

By this, you can check if it'll work or not and then do the real conversion once value is boolean true.

For more on this, please refer this answer: Parse v. TryParse

edited May 23 '17 at 10:25

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answered Nov 06 '14 at 04:37

Vishal Suthar

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Thanks, i tried this and it fixed the problem, any leads on what was causing it to not parse 77 ? – novice Nov 06 '14 at 04:39
it doesnt have currency symbols, i did check for white spaces, but to ToDouble() seems to work fine with white spaces . – novice Nov 06 '14 at 04:45
It has a \t character at the end – novice Nov 06 '14 at 04:48
Yes , but only at integer strings? it doesnt give the exception everytime, in fact generally runs fine – novice Nov 06 '14 at 04:51
Thats sad, any hints though about how I can get behind the cause of this? Have plenty of time – novice Nov 06 '14 at 04:54
Check in a `Debug` mode, that will surely give you an idea. – Vishal Suthar Nov 06 '14 at 04:55

score 2 · Answer 2 · answered Nov 06 '14 at 04:41

but i get a FormatException, when the string value is an integer value. In this particular case, when PricefromString = 77, i get the format exception.

No, you don't. Convert.ToDouble will work just fine with a string representing an integer, as you can see for yourself by running this code:

Console.WriteLine(Convert.ToDouble("77"));

It does in fact print out 77.

I would urge you to take a long, hard look at what precisely your input string is.

Convert.ToDouble() throws Format Exception

2 Answers2