#!/bin/sh
# This is a shar archive.
# The rest of this file is a shell script which will extract:
#
# 6_2.cmp 6_2a.c 6_2b.c makefile tst1.c tst2.c
#
# 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 23:07:46 EDT 1990
#
echo x - 6_2.cmp
sed 's/^X//' > 6_2.cmp << '!EOF!'
x=0123456789 [1]
x25=2345 [1]
x69=6789 [1]
x57=567 [1]
w=abcdefghijklmnop [1]
x=0123456789wxyz [1]
w(5)=fghijklmnop [1]
y=w(5,3)=fgh [1]
x(-5)=9wxyz [1]
x(-5,3)=9wx [1]
x(0)=0123456789wxyz [1]
x(0,2)=01 [1]
x(11,8)=xyz [1]
x(8,4)=89wx [1]
!EOF!
ls -l 6_2.cmp
echo x - 6_2a.c
sed 's/^X//' > 6_2a.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
// substring operator
// exercise 6.2
string string::operator()(int index, int count)
{
    char *s1 = p->s;
    int s1len = strlen(s1);

    // convert left index, if necessary
    if (index < 0)
	index += s1len;

    // left index past end of string
    else if (index >= s1len)
	return "";

    // convert count, if necessary
    int numleft = s1len - index;
    if (count > numleft || count < 0)
	count = numleft;

    // copy the substring
    char *s2 = new char[count + 1];
    strncpy(s2, s1+index, count);
    s2[count] = '\0';
    return s2;
}

!EOF!
ls -l 6_2a.c
echo x - 6_2b.c
sed 's/^X//' > 6_2b.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
string x = "0123456789"; // creates string "0123456789"
string x25 = x(2, 4);	 // creates string "2345"
string x69 = x(6);	 // creates string "6789"
string x57 = x(-5, 3);	 // creates string "567"
!EOF!
ls -l 6_2b.c
echo x - makefile
sed 's/^X//' > makefile << '!EOF!'
CC= CC -I. -I../../CC
ERROR= ../../error.o

all: tst1

tst1: 6_2a.c tst1.c 6_2b.c
	$(CC) -I. -D_6_2 -I../6.1dir tst1.c -o tst1 $(ERROR)

CMP= 6_2.cmp
OUT= 6_2.out

6_2.out: tst1 ;	./tst1 > 6_2.out

test: all $(OUT) $(CMP)
	cmp 6_2.cmp 6_2.out
	echo tests done
!EOF!
ls -l makefile
echo x - tst1.c
sed 's/^X//' > tst1.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
#include <strclass.h>
#include <6_2a.c>
main()
{
    {
#include "6_2b.c"
    cout << "x=" << x;
    cout << "x25=" << x25;
    cout << "x69=" << x69;
    cout << "x57=" << x57;
    }
    string w = "abcdefghijklmnop";
    string x = "0123456789wxyz";
    cout << "w=" << w;
    cout << "x=" << x;
    cout << "w(5)=" << w(5);
    string y = w(5,3);
    cout << "y=w(5,3)=" << y;
    cout << "x(-5)=" << x(-5);
    cout << "x(-5,3)=" << x(-5,3);
    cout << "x(0)=" << x(0);
    cout << "x(0,2)=" << x(0,2);
    cout << "x(11,8)=" << x(11,8);
    cout << "x(8,4)=" << x(8,4);
    return 0;
}
!EOF!
ls -l tst1.c
echo x - tst2.c
sed 's/^X//' > tst2.c << '!EOF!'
/* Copyright (c) 1990 by AT&T Bell Telephone Laboratories, Incorporated. */
/* The C++ Answer Book */
/* Tony Hansen */
/* All rights reserved. */
friend string& operator() (string& s1, int base, int len)
{
    char *s = new char[len];
    strcpy(s, &s1.p->s[base]);
    string st = s;
    delete s;
    return st;
}
!EOF!
ls -l tst2.c
# The following exit is to ensure that extra garbage 
# after the end of the shar file will be ignored.
exit 0