dennis@virtech.UUCP (Dennis P. Bednar) (02/14/90)
Posting-number: Volume 10, Issue 61
Submitted-by: dennis@virtech.UUCP (Dennis P. Bednar)
Archive-name: revcat_db
#! /bin/sh
# This file was wrapped with "dummyshar". "sh" this file to extract.
# Contents: revcat.c
echo extracting 'revcat.c'
if test -f 'revcat.c' -a -z "$1"; then echo Not overwriting 'revcat.c'; else
sed 's/^X//' << \EOF > 'revcat.c'
X/*
X * rev.c
X * dennis bednar
X * Cat a file backwards (last line first, first line last).
X * Done by a recursive procedure that minimizes chewing up
X * the stack space.
X */
X
X#include <stdio.h>
X
Xmain( argc, argv )
X char **argv;
X{
X FILE *ifp;
X int i;
X
X if (argc == 1) /* no arguments */
X rev_stream(stdin); /* so reverse stdin */
X else for (i = 1; i < argc; ++i) /* loop on file name args */
X {
X ifp = fopen( argv[i], "r");
X rev_stream( ifp ); /* reverse one file */
X fclose( ifp );
X }
X exit(0);
X}
X
X/* this is outside of rev_stream() function to avoid eating up stack space */
Xstatic char linebuf[ BUFSIZ ]; /* one line from file */
Xstatic FILE *rev_ifp; /* handle for file */
X
X/* Note that we want to minimize the stack space used by the recursive
X * function. So we use global static variables wherever possible.
X */
Xrev_stream( ifp )
X FILE *ifp;
X{
X rev_ifp = ifp; /* save in global for recursion */
X rev_stream_recursive(); /* do the work */
X}
X
X/*
X * recursively function to reverse lines of a stream 'rev_ifp'.
X */
Xrev_stream_recursive( )
X{
X char *cp;
X char *strdup();
X
X /* read one line then recurse to read the rest of the file.
X */
X if ( fgets(linebuf, sizeof(linebuf), rev_ifp ) ) /* !EOF */
X {
X cp = strdup( linebuf ); /* duplicate this line */
X rev_stream_recursive(); /* reverse the rest of file */
X fputs( cp, stdout ); /* now print this line */
X }
X}
X
Xchar *strdup( old )
X char *old;
X{
X char *new;
X extern char *malloc();
X
X new = malloc( strlen(old) + 1 ); /* room for null */
X strcpy( new, old );
X return new;
X}
EOF
chars=`wc -c < 'revcat.c'`
if test $chars != 1549; then echo 'revcat.c' is $chars characters, should be 1549 characters!; fi
fi
exit 0
--
Dennis Bednar uunet!virtech!dennis (703)760-3357(w) (703)437-4384(h)
Cable & Wireless, Tysons Corner VA