furlani@broadway.UUCP (John L. Furlani) (12/11/88)
In article <gables.352@umigw.miami.edu>, slores%gables.span@umigw.miami.edu (Stanislaw L. Olejniczak) writes: > PLEASE don't flame for posting too simple a question. I think the following > SHOULD work, but will not even compile: > while ( (c = getchar) != EOF) > chcnt++ += (c == '\n'); > The purpose is to count characters in a file. Each time a newline is This snippit of code should do it. It will count the newlines, but it won't count the returns. while ((c = getc(infile)) != EOF) if (c == '\r') chcnt++; As for 'chcnt++ += (c == '\n')', you can't assign what is being incremented to anything. This is different of course from '*count++ = 45' where the pointer is being incremented and the info contained in the pointer is being assigned. Flame? Who us? ____________ Disclaimer: "It's Mine! Mine! All Mine!!" John L. Furlani The University of South Carolina, Columbia SC (...!uunet!ncrlnk!ncrcae!broadway!furlani)
gwyn@smoke.BRL.MIL (Doug Gwyn ) (12/13/88)
In article <192@broadway.UUCP> furlani@broadway.UUCP (John L. Furlani) writes:
- This snippit of code should do it. It will count the newlines, but it
-won't count the returns.
- while ((c = getc(infile)) != EOF)
- if (c == '\r') chcnt++;
Oh, really?jrll@Portia.Stanford.EDU (john ralls) (12/15/88)
In article <192@broadway.UUCP> furlani@broadway.UUCP (John L. Furlani) writes: > >In article <gables.352@umigw.miami.edu>, slores%gables.span@umigw.miami.edu (Stanislaw L. Olejniczak) writes: >> PLEASE don't flame for posting too simple a question. I think the following >> The purpose is to count characters in a file. Each time a newline is > > if (c == '\r') chcnt++; True, this will count carriage returns and not newlines. In fact, it will count only carriage returns, which isn't what he had in mind. He wanted to count all characters, counting newlines as two characters (ie, cr/lf). Two ways to do it: if (c == '\n') chcnt +=2; else chcnt++; or for those who like the ternary operator (like me): c == '\n' ? chcnt +=2 : chcnt++; John
byron@pyr.gatech.EDU (Byron A Jeff) (12/19/88)
In article <4385@Portia.Stanford.EDU> jrll@Portia.stanford.edu (john ralls) writes: -In article <192@broadway.UUCP> furlani@broadway.UUCP (John L. Furlani) writes: -> ->In article <gables.352@umigw.miami.edu>, slores%gables.span@umigw.miami.edu (Stanislaw L. Olejniczak) writes: ->> PLEASE don't flame for posting too simple a question. I think the following ->> The purpose is to count characters in a file. Each time a newline is -> -> if (c == '\r') chcnt++; - -True, this will count carriage returns and not newlines. In fact, it -will count only carriage returns, which isn't what he had in mind. He -wanted to count all characters, counting newlines as two characters (ie, -cr/lf). Two ways to do it: - if (c == '\n') chcnt +=2; else chcnt++; - -or for those who like the ternary operator (like me): - - c == '\n' ? chcnt +=2 : chcnt++; - -John I think I like one of the following two better: chcnt += (c == '\n') ? 2 : 1; chcnt += 1 + (c == '\n'); Any comments one which one of the ones we've seen is most efficient? BAJ -- Another random extraction from the mental bit stream of... Byron A. Jeff Georgia Tech, Atlanta GA 30332 Internet: byron@pyr.gatech.edu uucp: ...!gatech!pyr!byron
ark@alice.UUCP (Andrew Koenig) (12/19/88)
In article <6959@pyr.gatech.EDU>, byron@pyr.gatech.EDU (Byron A Jeff) writes: > I think I like one of the following two better: > chcnt += (c == '\n') ? 2 : 1; > chcnt += 1 + (c == '\n'); > Any comments one which one of the ones we've seen is most efficient? If the problem is stated this way: count all the characters and count one extra for each newline then it seems to me that the most direct solution is: chcnt++; if (c == '\n') chcnt++; I suspect this is also the fastest on most machines. For example, here are instruction counts for the compiler on my machine: c=='\n' c!='\n' statement 6 6 chcnt += (c == '\n') ? 2 : 1; 5 4 chcnt += 1 + (c == '\n'); 4 3 chcnt++; if (c == '\n') chcnt++; This assumes that c and chcnt are both in registers. -- --Andrew Koenig ark@europa.att.com
mat@mole-end.UUCP (Mark A Terribile) (12/21/88)
> I think I like one of the following two better: > chcnt += (c == '\n') ? 2 : 1; > chcnt += 1 + (c == '\n'); > > Any comments one which one of the ones we've seen is most efficient? I certainly hope that the economy or practicality of your program does not hinge on this! What's more important, I think, is that unless you have good reason for using tricks (e.g. you are writing a ``compiler'' that produces C) your second form ... + ( c == n ) works because [ 0 1 ] is the ordered set of things you want to AND COINCIDENTALLY [ 0 1 ] is the range of the C equality operators. Making your code depend on such a coincidence forces the reader to be mindful of the coincidence. If the code is human-written to be human-read, I believe that it's very poor practice. Besides, any respectable compiler should generate the same code for both, modulo the assembly language label names (if such there be). -- (This man's opinions are his own.) From mole-end Mark Terribile
gwyn@smoke.BRL.MIL (Doug Gwyn ) (12/25/88)
In article <6959@pyr.gatech.EDU> byron@pyr.UUCP (Byron A Jeff) writes: >Any comments one which one of the ones we've seen is most efficient? Use the obvious ++chcnt; if ( c == '\n' ) ++chcnt; /* for implied CR */