maart@cs.vu.nl (Maarten Litmaath) (12/20/88)
barmar@think.COM (Barry Margolin) writes:
\1) When I've done this in other languages, I've used something like
\strlen("/") instead of the 2. Unfortunately, in C I'd still have to
\say "+1", which I'd then want to comment with /* leave room for the
\trailing null */, since I don't think there's an expression that will
\return the total space taken up by a string.
How about the following?
sizeof "/"
--
fcntl(fd, F_SETFL, FNDELAY): |Maarten Litmaath @ VU Amsterdam:
let's go weepin' in the corner! |maart@cs.vu.nl, mcvax!botter!maartkyriazis@rpics (George Kyriazis) (12/21/88)
In article <1827@solo11.cs.vu.nl> maart@cs.vu.nl (Maarten Litmaath) writes: >barmar@think.COM (Barry Margolin) writes: >\1) When I've done this in other languages, I've used something like >\strlen("/") instead of the 2. Unfortunately, in C I'd still have to >\say "+1", .... > >How about the following? > > sizeof "/" "/" is a pointer to a string containing a '/' and a '\0'. Therefore it seems to me that sizeof "/" will return the same value as sizeof( char * ). Comments?? George Kyriazis kyriazis@turing.cs.rpi.edu kyriazis@ss0.cicg.rpi.edu ------------------------------
guy@auspex.UUCP (Guy Harris) (12/22/88)
>"/" is a pointer to a string containing a '/' and a '\0'. "/" is not a pointer to a string; it is the string (i.e. an array of "char") itself. In some, but not all, contexts, the array is converted to a pointer to its first member; "argument of 'sizeof'" is not one of those contexts. (Check your K&R, or your dpANS.) >Therefore it seems to me that sizeof "/" will return the same value as >sizeof( char * ). This is, alas, apparently a mistake made by some C implementors; with any luck, there'll be a conformance-testing suite for the ANS when it comes out, and it will catch errors such as that.
poek@psu-cs.UUCP (Ken Poe) (12/30/88)
In article <29@rpi.edu> > kyriazis@rpics (George Kyriazis) writes: >In article <1827@solo11.cs.vu.nl> maart@cs.vu.nl (Maarten Litmaath) writes: >>barmar@think.COM (Barry Margolin) writes: >>\1) When I've done this in other languages, I've used something like >>\strlen("/") instead of the 2. Unfortunately, in C I'd still have to >>\say "+1", .... >> >>How about the following? >> >> sizeof "/" > >"/" is a pointer to a string containing a '/' and a '\0'. Therefore >it seems to me that sizeof "/" will return the same value as >sizeof( char * ). >Comments?? Only if your system has 2 byte pointers. The sizeof operator in C returns the size of the object (or of any object of that type for size of a type). When the object is a "string" (actually an array of char), the sizeof operator returns the number of bytes in the array. (including the null character ('\0') at the end of the "string") Try the following: main() { static char string[] = "abcd"; /* null char appended to string constants by the compiler */ printf("The size of string is %d\n", sizeof(string) ); printf("The size of \"/\" is %d\n", sizeof "/"); printf("The size of (char *) is %d\n", sizeof (char *) ); } On the VAX it's output is: The size of string is 5 The size of "/" is 2 The size of (char *) is 4 The only thing that is implementation dependent is the size of a pointer (32 bits on most systems) which can be 2 bytes. (near pointers in MSC etc). -- Kenneth N. Poe ATP, CFI | ARPANET: poek%cs.pdx.edu@relay.cs.net 16925 N.E Glisan St. | CSNET: poek@cs.pdx.edu Portland OR 97230-6252 | UUCP: {ucbvax,uunet,gatech} voice: (503) 252-1191 | !tektronix!psu-cs!poek cu: (503) 254-1009 | C-SERVE: 73477,2452 (when I get it working) ---------------------------------------------------------------------- I would much rather be on the ground wishing I were in the air than to be in the air wishing I were on the ground. -- Ken Poe ----------------------------------------------------------------------