|
dev
newsgroups
|
|||||||||||||||||||||||
|
|||||||||||||||||||||||
Convert String To GuidDoes somebody know if there's a faster way to convert a string to a guid, than:
Try gID = New Guid(myString) Catch ex As Exception gID = Guid.Empty End Try even if it's not clear that the string contains a valid guid? tia Martin Exception handling is expensive.... and this if this is not "exceptional",
as in....only happens in a blue moon, Id avoid the try/catch From http://geekswithblogs.net/jawad/archive/2005/05/20/GuidVerifier.aspx private static Regex isGuid = new Regex(@"^(\{){0,1}[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F ]{4}\-[0-9a-fA-F]{12}(\}){0,1}$", RegexOptions.Compiled); internal static bool IsGuid(string candidate, out Guid output) { bool isValid = false; output=Guid.Empty; if(candidate!=null) { if (isGuid.IsMatch(candidate)) { output=new Guid(candidate); isValid = true; } } return isValid; } rewrite that as your procedure. it avoids the try/catch, and gets the purpose accomplished. Show quote "Martin Moser" <MartinMo***@discussions.microsoft.com> wrote in message news:D5632D53-59D9-4434-8000-B3C97722288D@microsoft.com... > Does somebody know if there's a faster way to convert a string to a guid, than: > > Try > gID = New Guid(myString) > Catch ex As Exception > gID = Guid.Empty > End Try > > even if it's not clear that the string contains a valid guid? > > tia > Martin Hi,
I've already tried to use RegularExpressions. RegEx is faster if the string doesn't contain a valid guid, but it's slower if the string contains a valid guid. Show quote "sloan" wrote: > Exception handling is expensive.... and this if this is not "exceptional", > as in....only happens in a blue moon, Id avoid the try/catch > > From > http://geekswithblogs.net/jawad/archive/2005/05/20/GuidVerifier.aspx > > private static Regex isGuid = new > Regex(@"^(\{){0,1}[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F > ]{4}\-[0-9a-fA-F]{12}(\}){0,1}$", RegexOptions.Compiled); > > internal static bool IsGuid(string > candidate, out Guid output) > > { > > bool isValid = false; > > output=Guid.Empty; > > if(candidate!=null) > > { > > > > if > (isGuid.IsMatch(candidate)) > > { > > > output=new Guid(candidate); > > > isValid = true; > > } > > } > > return isValid; > > } > > > > rewrite that as your procedure. it avoids the try/catch, and gets the > purpose accomplished. > > > > "Martin Moser" <MartinMo***@discussions.microsoft.com> wrote in message > news:D5632D53-59D9-4434-8000-B3C97722288D@microsoft.com... > > Does somebody know if there's a faster way to convert a string to a guid, > than: > > > > Try > > gID = New Guid(myString) > > Catch ex As Exception > > gID = Guid.Empty > > End Try > > > > even if it's not clear that the string contains a valid guid? > > > > tia > > Martin > > > You have three options:
1. Use Guid(string) constructor 2. Use RegEx 3. Use custom string parser (sequential and not RegEx based) You are not happy with (1) and (2). (3) is the only option left... but that may end up being a copy of (1) However, if the data that you have is in some specific format, say, '{' is always present or '-' is always absent, your (3) may be faster than (1) (1) looks for all possibilities, presence of '{', presence of '-' etc making it slow. No other option comes to my mind than the above. Show quote "Martin Moser" <MartinMo***@discussions.microsoft.com> wrote in message news:AFB26257-46FA-46B7-AD56-FBA58701EFF1@microsoft.com... > Hi, > > I've already tried to use RegularExpressions. RegEx is faster if the > string > doesn't contain a valid guid, but it's slower if the string contains a > valid > guid. > > > "sloan" wrote: > >> Exception handling is expensive.... and this if this is not >> "exceptional", >> as in....only happens in a blue moon, Id avoid the try/catch >> >> From >> http://geekswithblogs.net/jawad/archive/2005/05/20/GuidVerifier.aspx >> >> private static Regex isGuid = new >> Regex(@"^(\{){0,1}[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F >> ]{4}\-[0-9a-fA-F]{12}(\}){0,1}$", RegexOptions.Compiled); >> >> internal static bool IsGuid(string >> candidate, out Guid output) >> >> { >> >> bool isValid = false; >> >> output=Guid.Empty; >> >> if(candidate!=null) >> >> { >> >> >> >> if >> (isGuid.IsMatch(candidate)) >> >> { >> >> >> output=new Guid(candidate); >> >> >> isValid = true; >> >> } >> >> } >> >> return isValid; >> >> } >> >> >> >> rewrite that as your procedure. it avoids the try/catch, and gets the >> purpose accomplished. >> >> >> >> "Martin Moser" <MartinMo***@discussions.microsoft.com> wrote in message >> news:D5632D53-59D9-4434-8000-B3C97722288D@microsoft.com... >> > Does somebody know if there's a faster way to convert a string to a >> > guid, >> than: >> > >> > Try >> > gID = New Guid(myString) >> > Catch ex As Exception >> > gID = Guid.Empty >> > End Try >> > >> > even if it's not clear that the string contains a valid guid? >> > >> > tia >> > Martin >> >> >> > 3. Use custom string parser (sequential and not RegEx based) For this option, you could always use a freely available tool (eg. Salamander, dotnet Reflector), to see exactly what "public Guid(string str)" does. This would ensure that your custom code worked exactly like the framework's code, except you'd change your version so that it would not raise exceptions and return false instead. Stephen  |
|||||||||||||||||||||||
Other interesting topics