Programming Forums > Application Development > C#

Master · Nov 21st, 2006, 8:37 AM

I think he think he is using VB.NET because it automatically does the conversion

lectricpharaoh · Nov 21st, 2006, 12:14 PM

I prefer using the Parse() or TryParse() methods instead- the former is more appropriate if you know the number is okay to convert, while the latter is better for any 'un-vetted' input (particularly user input).

Parse() returns the converted value if it was successful, or otherwise throws an exception. TryParse() returns a bool that is true on success, and fills in the value via an out parameter. Example:

(Toggle Plain Text)

double int value;
bool success;

value = double.Parse("123.45");  // this line will be okay
value = double.Parse("abc.de");  // throws exception
success = double.TryParse("123.45", out value);  // returns true, value is filled in
success = double.TryParse("abc.de", out value);  // returns false, value is unchanged

[edit] I forgot to mention that all the basic types (char, int, etc) have this method. It's actually a method of the 'boxed' classes like Double as opposed to double, but the .NET runtime will handle the boxing/unboxing of data, so you don't need to worry about it. So, in the future, if you ever need to convert a string to a number, these two methods are your best friends. [/edit]
[edit2] Well, I didn't read the thread all the way through, and failed to notice the problem was actually converting the other way around. So yeah, ToString() as several people mentioned works for that (and will work on every single type, although you might not always get the text you expect). [/edit2]

Nov 21st, 2006, 12:14 PM	#12
lectricpharaoh Caffeinated Neural Net Join Date: Jun 2005 Location: Dry west coast of Canada Posts: 1,010 Rep Power: 5	I prefer using the Parse() or TryParse() methods instead- the former is more appropriate if you know the number is okay to convert, while the latter is better for any 'un-vetted' input (particularly user input). Parse() returns the converted value if it was successful, or otherwise throws an exception. TryParse() returns a bool that is true on success, and fills in the value via an out parameter. Example: (Toggle Plain Text) double int value; bool success; value = double.Parse("123.45"); // this line will be okay value = double.Parse("abc.de"); // throws exception success = double.TryParse("123.45", out value); // returns true, value is filled in success = double.TryParse("abc.de", out value); // returns false, value is unchanged double int value; bool success; value = double.Parse("123.45"); // this line will be okay value = double.Parse("abc.de"); // throws exception success = double.TryParse("123.45", out value); // returns true, value is filled in success = double.TryParse("abc.de", out value); // returns false, value is unchanged [edit] I forgot to mention that all the basic types (char, int, etc) have this method. It's actually a method of the 'boxed' classes like Double as opposed to double, but the .NET runtime will handle the boxing/unboxing of data, so you don't need to worry about it. So, in the future, if you ever need to convert a string to a number, these two methods are your best friends. [/edit] [edit2] Well, I didn't read the thread all the way through, and failed to notice the problem was actually converting the other way around. So yeah, ToString() as several people mentioned works for that (and will work on every single type, although you might not always get the text you expect). [/edit2] __________________ And once again, Probability proves itself willing to sneak into a back alley and service Drama as would a copper-piece harlot. - Vaarsuvius, Order of the Stick

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Nov 21st, 2006, 8:37 AM	#11
Master Programmer Join Date: Sep 2005 Location: GA Posts: 99 Rep Power: 3	I think he think he is using VB.NET because it automatically does the conversion

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Programming Forums > Application Development > C#

String to double