NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/comp/lang/c/19524

Text File | 1993-01-11 | 2.1 KB | 63 lines

Newsgroups: comp.lang.c
Path: sparky!uunet!spool.mu.edu!uwm.edu!linac!unixhub!ditka!eagercon!eagercon!eager
From: [e-mail] (Michael J. Eager)
Subject: Re: how to write C code so that redirection works
Message-ID: <[e-mail]>
Sender: [e-mail] (Operator)
Reply-To: [e-mail]
Organization: Eager Consulting
References: <[e-mail]>
Date: Mon, 11 Jan 1993 06:17:58 GMT
Lines: 50

In article [e-mail], [e-mail] (Stephen H. Kawamoto) writes:
>i have a minor problem with C in that when i have a compiled file, FOO
>FOO <infile >outfile
>wont work. it 'hangs' and a ctrl-c or ctrl-break results in the outfile
>having more bytes in it (stuff from the uninitialized memory space i think).
>
>it's the CTOPAS.C source, which turns Pascal into Pascal-like pseudocode (not
>true Turbo Pascal in any case).
>
>here's the main where the problem might lie:
>
>>>
>>> void main()
>>> {
>>>    char c, *letter, word[100];
>>>    int wordlnth;
>>>
>>>    letter=word;
>>>    wordlnth=0;
>>>    while((c=getchar()) != EOF) {
>>>       if(isalpha(c)) letter[wordlnth++]=c;
>>>       else {
>>>          if(wordlnth>0) {            /* word ready to check
>>> */
>>>             letter[wordlnth]='\0';
>>>             wtest(word);             /* pass or replace it
>>> */
>>>             wordlnth=0;              /* reset index */
>>>          }
>>>          ctest(c);                   /* process following
>>> character */
>>>       }
>>>    }
>>> }   /* Note:  the last word in the file will be missed if it
>>> followed by EOF with no intervening nonalphanumeric
>>> characters.  This is not a problem for Pascal or C source
>>> files.  */


Try changing the declaration of c from char to int.  Most implementations
of getchar return a char sized value for the 256 character values which can fit
in a byte, but the EOF value is outside this range (often -1).  When you save
it in char c, it gets truncated and is not recognized as the end of file.


---
Michael J. Eager        [e-mail]
Eager Consulting        [phone]
1960 Park Boulevard, Palo Alto, CA 94306-1141