V053MDHL%UBVMS.BITNET@wiscvm.wisc.edu (03/27/87)
I am writing a program that manipulates data inside a data file. One of
the manipulations requires scanning the data strings (character) for the pres-
ence of newline characters. I am using <fgets> in the program, but I can not
get it to work. I am working on a Digital VAX. I have noticed a few points :
[1] The <fgets> function returns a pointer to the first character in
the string. It was my belief that the pointer should point to the
last <\0> character, as I already know where the string begins.
[2] In scanning the string for characters, I can compare with neither
"\n" or "\0", as neither of these characters, while actually pre-
sent in the strings, registers when compared.
Is the compiler wrong? Any help in this would be greatly appreciated.
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"Mutant Hunter" V053MDHL@UBVMSCamos@instable.UUCP (03/27/87)
In article <5902@brl-adm.ARPA> V053MDHL%UBVMS.BITNET@wiscvm.wisc.edu writes: > ... I am working on a Digital VAX ... This is not enough, there are at least 6 different O.S. on vaxen; I suspect however that 'fgets' should behave the sames way on all. > [1] The <fgets> function returns a pointer to the first character in > the string. It was my belief that the pointer should point to the > last <\0> character, as I already know where the string begins. This is done so you can do things like strcmp("END", fgets(...)) > [2] In scanning the string for characters, I can compare with neither > "\n" or "\0", as neither of these characters, while actually pre- > sent in the strings, registers when compared. What do you mean 'does not register when compared'? How are the comparisons done? are you comparing to '\n' or '\0' (notice the *single* quotes)? -- Amos Shapir National Semiconductor (Israel) 6 Maskit st. P.O.B. 3007, Herzlia 46104, Israel Tel. (972)52-522261 amos%nsta@nsc.com {hplabs,pyramid,sun,decwrl} 34.48'E 32.10'N
chris@mimsy.UUCP (03/27/87)
In article <5902@brl-adm.ARPA> V053MDHL%UBVMS.BITNET@wiscvm.wisc.edu writes: >[1] The <fgets> function returns a pointer to the first character in > the string. It was my belief that the pointer should point to the > last <\0> character .... fgets returns either its first argument or NULL. Where did you acquire this belief? >[2] In scanning the string for characters, I can compare with neither > "\n" or "\0", as neither of these characters, while actually pre- > sent in the strings, registers when compared. From the way you phrased this, I suspect you have a test that looks like this: if (c == "\n" || c == "\0") If `c' is a character or integer value, this should elicit a warning from the compiler, since "\n" and "\0" become pointer values. Change the test to if (c == '\n' || c == '\0') 'x' produces an integer constant; "string" produces a pointer to an unnamed aggregate constant, type array N of char, where N is strlen(string)+1. -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690) UUCP: seismo!mimsy!chris ARPA/CSNet: chris@mimsy.umd.edu