|
I have a string that contains some text. I want to check if the text can be converted into an integer. At the moment my code looks like this:
bool isInt = true;
try
{
int intValue = int.Parse(stringValue);
}
catch(Exception e)
{
isInt = false;
}
At the end of the code isInt will contain whether the string value can be converted to an int or not.
Is there a better way to do this? I don't like having to catch an exception when I expect that many string values will not be convertable to an int. It seems very inefficient.
|
|
|
|
|
It's the most secure way to convert a string to an int.
Why don't you put just all assignments into one single try-catch block?
regards
modified 12-Sep-18 21:01pm.
|
|
|
|
|
Greeeg wrote:
Why don't you put just all assignments into one single try-catch block?
I don't want to convert it. This is part of some validation code. I just want to see if it is possible to convert it.
|
|
|
|
|
Since someone voted my previous reply a 3 I can only guess that I didn't explain myself very well.
I don't have multiple assignments. I only want to check one value and I only want to check if it is possible to convert it to an integer. I do not want to do an actual conversion.
If further explanation is needed, I'll be happy to explain more.
|
|
|
|
|
|
A double is no use to me. It will accept as valid values that are not valid integers. It is a pity, however, that there doesn't seem to be an equivalent for Int32.
|
|
|
|
|
I suggest you actually read the documentation.
There's a flag controlling what kind of numbers to parse.
mav
|
|
|
|
|
mav.northwind wrote:
I suggest you actually read the documentation.
I did read the documentation, but it does not explain on the TryParse page that it can be used to check integers. That is pretty useless documentation if you have to delve into sub-documents to find something that should have been at least mentioned on the first page even if there was no details about it.
Thank you for at least prodding me to read further because I did eventaully find the answer on this route. I hope you don't mind my little rant at the documentation. MSDN is usually very good.
|
|
|
|
|
Glad to hear you found the information.
The NumberStyles enumeration is in fact not explained on the page of TryParse, but that's the standard way MSDN is built. It's a separate type, so it's documented separately. With a proper link, though.
Anyway, once you actually have found the information you needed it's usually there where you'd expect it to be. But the location is only obvious _after_ you've found it, not when you're actually trying to find it 
mav
|
|
|
|
|
|
I don't know how fast this is compared to the other options, but this way won't throw any exceptions, which are inefficient. Using regular expressions to validate input is a common practice:
bool isNumber = System.Text.RegularExpressions.Regex.IsMatch(stringValue, "[0-9]");
Tech, life, family, faith: Give me a visit.
I'm currently blogging about: Conversation With a Muslim
Judah Himango
|
|
|
|
|
But you have to be careful with regular expressions, since they are only testing what you think should be a valid int, not what really may be valid. For example, the regular expression you offered won't do too well on negative values.
Matt Gerrans
|
|
|
|
|
What would be better is just catching an InvalidCastException, instead of anything that may go wrong.
Christian Graus - Microsoft MVP - C++
|
|
|
|
|
Thanks for your suggestion, I realise that I should only catch the specific case. However, I don't expect the failure of the conversion to be an exceptional case. I expect that the string does not conform regularly. That is why I didn't want to use a method that throws exceptions when the conversion fails.
I got an answer about Double.TryParse that returns a Boolean value and can be set to convert only integers that I'm going to use.
|
|
|
|
|
Andy MacAngus wrote:
However, I don't expect the failure of the conversion to be an exceptional case.
Exceptions don't mean you can only use them when they will rarely throw.
Andy MacAngus wrote:
Double.TryParse
Yeah, I thought there was something like that, but couldn't remember the details.
Christian Graus - Microsoft MVP - C++
|
|
|
|
|
Christian Graus wrote:
Exceptions don't mean you can only use them when they will rarely throw.
What I mean is that exceptions are expensive and I expect that in the validation code I am writing that there will be a lot of bad data and I would like the validation code to work quickly. 
|
|
|
|
|
I want to know how can I obtain my own IP address when I connect to the internet via dialup modem & ISP in c#.
Enayat Masoumi
|
|
|
|
|
What do you mean by "obtain my own IP address"? When you connect to your ISP, the address is automatically assigned to you by the ISP. So what's the problem?
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
|
|
|
|
|
|
Why do I detect a homework assignment here?
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
|
|
|
|
|
i will start working on a project used to Transfer specefic Data From Oracle DB to SQL Server 2005
//---Case
2 programs the first one is using Oracle9i Database
the Second one is using MSSQL server 2000
//---
I want to transfer Data From the Oracle DB to my SQL Server Database where the First application start saving that data to Oracle
//---Summery (Dump) Oracle Table => SQL Table
Any Thoughts....
agmb
|
|
|
|
|
Hi
I have a Rich Text Box where I need to highlight individual lines. I have to have word wrap disabled as I have long lines, but when I try setting a selection it scrolls to the end of the line.
Can anyone tell me how I can highlight a line of text in a Rich Text Box, either by keeping the caret at the start of the selection, or by changing the background colour of the selection?
TIA.
|
|
|
|
|
You have the right idea, just need to add a couple of steps.
First, save the current SelectionStart and SelectionLength values of the RTB before you start your color update. Then call .SuspendLayout(), do your color update just like you have been, set the SelectionStart and SelectionLength values back to what you saved, then call .ResumeLayout(). This should do what you want.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
|
|
|
|
|
Hmmm... maybe I didn't explain myself very well. I have a file in which I have a number of lines which are highlighted by changing their (foreground) colour - this is achieved by rtxtBox.Select(LineOffset,LineLength) and then changing rtxtBox.SelectionColor.
The user can move automatically between these lines by the use of up and down buttons - I'm currently just showing which of these lines they are on by moving the caret with rtxtBox.Select(LineOffset,0). I want to highlight the line by setting the selection to the whole line, but if I do rtxtBox.Select(LineOffset,LineLength) it scrolls to the end of the line.
It seems to me the only two solutions would be to:
a) change the background colour of the line (which appears not to be possible), or
b) move the caret back to the start of the line (which only seems to be possible by calling rtxtBox.Select(LineOffset,0), thereby removing the highlight).
Any ideas?
Ian.
|
|
|
|
|
That definately changes things. You really can't depend on the RTB's Selection highlight to work the way you need it to. You'll have to implement your won line tracking code and draw the highlight yourself. In which case, my original suggestion for changing the textcolor still stands. You just need to add code to track which line is currently selected and manage the drawing of the highlight. You've already got most of the pieces, including the buttons to move the highlight up and down.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
