#!/bin/sh
# This is a shar archive.
# The rest of this file is a shell script which will extract:
#
# 2_6.c 2_6.cmp 2_6a.c 2_6b.c 2_6c.c makefile
#
# To extract the files from this shell archive file simply
# create a directory for this file, move the archive file
# to it and enter the command
#
#	sh filename
# 
# The files will be extracted automatically.
# Note: Do not use csh.
#
# Archive created: Mon Jul 30 22:57:08 EDT 1990
#
echo x - 2_6.c
sed 's/^X//' > 2_6.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// print the bits of a null character pointer
#include <stream.h>
#include <limits.h>

#include "2_6a.c"	/* EXPAND */

#include "2_6c.c"	/* EXPAND */

void prbits(char byte)
{
    cout << "0b";

    for (unsigned long mask = HIBIT(unsigned char);
	 mask != 0; mask >>= 1)
	if ((byte & mask) != 0)
	    cout << "1";

	else
	    cout << "0";
}

int main(int, char**)
{
#include "2_6b.c"	/* EXPAND4 */

    for (int i = 0; i < sizeof(char*); i++)
	{
	cout << "byte " << i << " = ";
	prbits(pi.byte[i]);
	cout << "\n";
	}

    return 0;
}
!EOF!
ls -l 2_6.c
echo x - 2_6.cmp
sed 's/^X//' > 2_6.cmp << '!EOF!'
byte 0 = 0b00000000
byte 1 = 0b00000000
byte 2 = 0b00000000
byte 3 = 0b00000000
!EOF!
ls -l 2_6.cmp
echo x - 2_6a.c
sed 's/^X//' > 2_6a.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
union ptr_bits 
{
    char *ptr;
    char byte[sizeof(char*)];
};
!EOF!
ls -l 2_6a.c
echo x - 2_6b.c
sed 's/^X//' > 2_6b.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
ptr_bits pi;
pi.ptr = 0;
!EOF!
ls -l 2_6b.c
echo x - 2_6c.c
sed 's/^X//' > 2_6c.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
#undef BITS		/* DELETE */
#define BITS(type)    (CHAR_BIT * (int)sizeof(type))
#define HIBIT(type)   ((type)(((type) 1) << \
		      (BITS(type) - 1)))
!EOF!
ls -l 2_6c.c
echo x - makefile
sed 's/^X//' > makefile << '!EOF!'
CC= CC -I. -I../../CC
all: 2_6

2_6: 2_6.c 2_6a.c 2_6b.c 2_6c.c
	$(CC) 2_6.c -o 2_6

test: all 2_6.cmp
	2_6 > 2_6.out
	cmp 2_6.out 2_6.cmp
	echo tests done
!EOF!
ls -l makefile
# The following exit is to ensure that extra garbage 
# after the end of the shar file will be ignored.
exit 0