Question

This line of code:

Console.WriteLine(Convert.ToInt32(“23,23”) + 1);

Throws an exception.
This line of code:

Console.WriteLine(Convert.ToDouble(“23,23”) + 1);

Prints 2324.

Does anybody know why this is the case? I wouldn’t think that anything good could come of the second conversion.

Answer 1

From the MSDN documentation of System.Double.Parse:

The s parameter can contain […] a string of the form:

[ws][sign][integral-digits[,]]integral-digits[.[fractional-digits]][e[sign]exponential-digits][ws]

Here, the comma (,) stands for “[a] culture-specific thousands separator symbol”.

To summarize: If your current culture’s thousands separator symbol appears anywhere in the string, it is ignored by Double.Parse (which is invoked internally by Convert.ToDouble).

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Int32.Parse(string), on the other hand, does not allow thousands separators in the string:

[ws][sign]digits[ws]

which is why your first example throws an exception. You can change this behavior for both Double.Parse and Int32.Parse by using an overload that allows you to specify NumberStyles, as explained by the other answers.