// mystring.c
// define and test mystring type.
// Created: Thu 10 March 2005 at 12:56 UT+11.

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>

// Data Type mystring
typedef struct {char *str; int maxlen;} mystring;

// Function prototypes
mystring create_string (int);
void free_string (mystring);
void prompt_read_string (mystring*);
void read_string2 (mystring*);
void use_strings (void);
void write_string (mystring);
void write_named_string (char name3[], mystring s7);

int
main (void)
{
	use_strings();
	return 0;
}

void
use_strings (void)
{
	mystring s1 = create_string (5);

	prompt_read_string (&s1);
	write_named_string ("s1", s1);

	free_string (s1);
}

mystring
create_string (int maxsize)
{
	mystring s0;
	if (maxsize <= 0)
	{
		fprintf (stderr, "create_string called with nonpositive maxsize! \n");
		s0.maxlen = 0;
		s0.str = 0;
	}
	else
	{
		s0.maxlen = maxsize;
		s0.str = calloc (maxsize+1, sizeof (char));
	}
	return s0;
}

void
free_string (mystring s0)
{
	free (s0.str);
	s0.maxlen = 0;
}

void
read_string2 (mystring * ps2)
{
	if (!ps2)
		fprintf (stderr, "read_string2 called with string pointer NULL ! \n");
	else if (ps2->str == 0)
		fprintf (stderr, "read_string2 called with unallocated mystring ! \n");
	else
	{
		// PRECONDITION:  ps2 is already allocated.
		int i;
		for (i=0; i < ps2->maxlen; i++)
		{
			int ch = getchar();
			if (isspace (ch))
				break;
			ps2->str[i] = ch;
		}
		ps2->str[i] = '\0';
		// POSTCONDITION:  *ps2->str is a valid C string of length <= maxlen;
	}
}

void
prompt_read_string (mystring * ps3)
{
	printf ("Please type in a string: ");
	read_string2 (ps3);
}

void
write_string (mystring s0)
{
	if (!s0.str)
		fprintf (stderr, "write_string called with unallocated mystring! \n");
	else
	{
		int i;
		for (i=0; i < s0.maxlen && s0.str[i] != '\0'; i++)
			putchar (s0.str[i]);
	}
}

void
write_named_string (char name3[], mystring s7)
{
	printf ("mystring %s = `", name3);
	write_string (s7);
	printf ("' \n");
}

// EOF mystring.c