# You may have to edit this file to delete header lines produced by
# mailers or news systems from this file (all lines before these shell
# comments you are currently reading).

# Shell archive made by dwjones on Fri Oct 27 10:47:57 AM CDT 2023

# To install this software on a UNIX system:
#  1) create a directory (e.g. with the shell command mkdir stuff)
#  2) change to that directory (e.g. with the command cd stuff),
#  3) direct the remainder of this text to sh (e.g. sh < ../savedmail).
# This will make sh create files in the new directory; it will do
# nothing else (if you're paranoid, you should scan the following text
# to verify this before you follow these directions).  Then read README
# in the new directory for additional instructions.
cat > main.c <<\xxxxxxxxxx
/* main.c -- test my class implementing stack of strings */
#include <stdio.h>

#include "stack.h"

unsigned int main() {
    stackhandle mystack = newstack();
    push( mystack, " zebra.\n" );
    push( mystack, " pet" );	/* logically, this is mystack.push( " pet" ) */
    push( mystack, " my" );
    push( mystack, " like" );
    push( mystack, "I" );
    while( !empty( mystack ) ) { /* logically, this uses !mystack.empty() */
	printf( "%s", pop( mystack ) );
    }
    return 0;
}
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cat > stack.c <<\xxxxxxxxxx
/* stack.c -- implements a non-polymorphic stack class */
#include <stdio.h>
#include <stdlib.h>

#include "stack.h"

/* private definition of a stack element */
struct stackelement {
    const char * str; /* the string in this stack element */
    struct stackelement * next; /* link to rest of stack */
};

/* details of a stack object */
struct stack {
    struct stackelement * top;
};
/* struct stack * stackhandle; this definition is given in stack.h */

stackhandle newstack() {
    stackhandle s = malloc( sizeof( struct stack ) );
    s->top = NULL;
}

void push( stackhandle s, const char * str ) { /* push str on stack s */
    struct stackelement * new = malloc( sizeof( struct stackelement ) );
    new->str = str;
    new->next = s->top;
    s->top = new;
}

const char * pop( stackhandle s ) { /* return the top of stack s and pop */
    const char * ret = s->top->str;
    struct stackelement * old = s->top;
    s->top = s->top->next;
    free( old );
    return ret;
}

int empty( stackhandle s ) { /* reports 1 if stack empty, else 0 */
    return s->top == NULL;
}
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cat > stack.h <<\xxxxxxxxxx
/* stack.h -- interface to a non-polymorphic stack class */

struct stack; /* details given and visible only in stack.c */

typedef struct stack * stackhandle; /* all stack users use these */

stackhandle newstack(); /* constructor for stack objects */

void push( stackhandle s, const char * str ); /* push str on stack s */
const char * pop( stackhandle s ); /* return the top of stack s and pops it */
int empty( stackhandle s ); /* reports 1 if stack empty, else 0 */
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cat > Makefile <<\xxxxxxxxxx
# Makefile for dumb stack demo

demo: main.o stack.o
	cc -o demo main.o stack.o

main.o: main.c stack.h
	cc -c main.c

stack.o: stack.c stack.h
	cc -c stack.c

# make clean -- removes all files created by make
clean:
	rm -f *.o
	rm -f demo
	rm -f shar
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