Top/Again instruction?
in [Learn C or C++]
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From: waltbrad on 26 Dec 2007 12:05 I'm trying to read a GREP program written in C for windows. This is written by Alan R. Feuer. Tried to find it on the web, but couldn't. In a function called patternMatch he uses the instructions Top: and Again: I haven't been coding long and have never run into this. Nor can I seem to find much information on the web about them. But here is how it is used in this snippet: BOOL patternMatch (char *pattern, char *string) /* Return TRUE if pattern matches string. */ { register char pc, sc; char *pat; BOOL anchored; if (anchored = (*pattern == ANCHOR)) ++pattern; Top: /* Once per char in string. */ pat = pattern; Again: pc = *pat; sc = *string; Can anyone tell me about these or point me to a page on it? TIA
From: waltbrad on 26 Dec 2007 12:08 On Dec 26, 12:05 pm, waltbrad <waltb...(a)hotmail.com> wrote: > I'm trying to read a GREP program written in C for windows. This is > written by Alan R. Feuer. Tried to find it on the web, but couldn't. > > In a function called patternMatch he uses the instructions Top: and > Again: > > I haven't been coding long and have never run into this. Nor can I > seem to find much information on the web about them. > > But here is how it is used in this snippet: > > BOOL > patternMatch (char *pattern, char *string) > /* Return TRUE if pattern matches string. */ > { > register char pc, sc; > char *pat; > BOOL anchored; > > if (anchored = (*pattern == ANCHOR)) > ++pattern; > > Top: /* Once per char in string. */ > pat = pattern; > > Again: > pc = *pat; > sc = *string; > > Can anyone tell me about these or point me to a page on it? > > TIA Sorry. He also concludes with a Success: instruction. So I'm actually looking for Top: Again: Success:
From: waltbrad on 26 Dec 2007 13:21 On Dec 26, 12:08 pm, waltbrad <waltb...(a)hotmail.com> wrote: > On Dec 26, 12:05 pm, waltbrad <waltb...(a)hotmail.com> wrote: > > > > > I'm trying to read a GREP program written in C for windows. This is > > written by Alan R. Feuer. Tried to find it on the web, but couldn't. > > > In a function called patternMatch he uses the instructions Top: and > > Again: > > > I haven't been coding long and have never run into this. Nor can I > > seem to find much information on the web about them. > > > But here is how it is used in this snippet: > > > BOOL > > patternMatch (char *pattern, char *string) > > /* Return TRUE if pattern matches string. */ > > { > > register char pc, sc; > > char *pat; > > BOOL anchored; > > > if (anchored = (*pattern == ANCHOR)) > > ++pattern; > > > Top: /* Once per char in string. */ > > pat = pattern; > > > Again: > > pc = *pat; > > sc = *string; > > > Can anyone tell me about these or point me to a page on it? > > > TIA > > Sorry. He also concludes with a Success: instruction. So I'm actually > looking for Top: Again: Success: Okay, I see. First time I've ever had to deal with "go to" branching. So, you can use just anything as a label? so long as it's followed by a colon?
From: Ivan Novick on 26 Dec 2007 13:39 On Dec 26, 10:21 am, waltbrad <waltb...(a)hotmail.com> wrote: > On Dec 26, 12:08 pm, waltbrad <waltb...(a)hotmail.com> wrote: > > > > > On Dec 26, 12:05 pm, waltbrad <waltb...(a)hotmail.com> wrote: > > > > I'm trying to read a GREP program written in C for windows. This is > > > written by Alan R. Feuer. Tried to find it on the web, but couldn't. > > > > In a function called patternMatch he uses the instructions Top: and > > > Again: > > > > I haven't been coding long and have never run into this. Nor can I > > > seem to find much information on the web about them. > > > > But here is how it is used in this snippet: > > > > BOOL > > > patternMatch (char *pattern, char *string) > > > /* Return TRUE if pattern matches string. */ > > > { > > > register char pc, sc; > > > char *pat; > > > BOOL anchored; > > > > if (anchored = (*pattern == ANCHOR)) > > > ++pattern; > > > > Top: /* Once per char in string. */ > > > pat = pattern; > > > > Again: > > > pc = *pat; > > > sc = *string; > > > > Can anyone tell me about these or point me to a page on it? > > > > TIA > > > Sorry. He also concludes with a Success: instruction. So I'm actually > > looking for Top: Again: Success: > > Okay, I see. First time I've ever had to deal with "go to" branching. > So, you can use just anything as a label? so long as it's followed by > a colon? Ummm... yes ... i guess it can't be another reserved word like?: for: but otherwise yeah, those are just labels. Regards, Ivan Novick http://www.0x4849.net
From: Bart van Ingen Schenau on 26 Dec 2007 14:13
waltbrad wrote: > I'm trying to read a GREP program written in C for windows. This is > written by Alan R. Feuer. Tried to find it on the web, but couldn't. > > In a function called patternMatch he uses the instructions Top: and > Again: > > I haven't been coding long and have never run into this. Nor can I > seem to find much information on the web about them. > > But here is how it is used in this snippet: > > BOOL > patternMatch (char *pattern, char *string) > /* Return TRUE if pattern matches string. */ > { > register char pc, sc; > char *pat; > BOOL anchored; > > if (anchored = (*pattern == ANCHOR)) > ++pattern; > > Top: /* Once per char in string. */ > pat = pattern; > > Again: > pc = *pat; > sc = *string; > > Can anyone tell me about these or point me to a page on it? These are not actually instructions in the C and C++ languages, but they are markers (labels) in the source code that you can jump to with a goto statement. In some other part of the patternMatch() function, you will likely see an instruction goto Top; or goto Again; Lookup 'goto' and 'label' in your favourite reference book, and remember that it usually makes the code a lot harder to digest when goto is being used. > > TIA Bart v Ingen Schenau -- a.c.l.l.c-c++ FAQ: http://www.comeaucomputing.com/learn/faq c.l.c FAQ: http://c-faq.com/ c.l.c++ FAQ: http://www.parashift.com/c++-faq-lite/ |