gistfile1.cpp

#include <cstdio>
#include <cstdlib>

int strlen(char *text)
{
	int i;
	for(i = 0; text[i] != '\0'; i++);
	return i;
}


char up(char ch)
{
	if(ch >= 'a' && ch <= 'z')
		return ch = 'A' + (ch - 'a');
	return ch;
}


int strcmp(char *a, char *b)
{
	for(int i = 0; i < strlen(a) && i < strlen(b); i++)
	{
		if(up(a[i]) < up(b[i]))
			return -1;
		else if(up(a[i]) > up(b[i]))
			return 1;
	}
	if(strlen(a) < strlen(b))
		return -1;	
	else if(strlen(a) > strlen(b))
		return 1;
	return 0;
}

struct Node
{
	char *value;
	Node *next, *prev;

	Node(char *val)
	{
		value = new char[1000];
		for(int i = 0; i < strlen(val); i++)
			value[i] = val[i];
		value[strlen(val)] = '\0';

		next = prev = NULL;
	}
};

Node *list;

void add(char *word)
{
	if(list == NULL)
		list = new Node(word);
	else
	{
		Node *cur = list, *prev_cur = NULL, *elem = new Node(word);
		while(cur != NULL && strcmp(cur->value, word) < 0)
		{
			prev_cur = cur;
			cur = cur->next;
		}

		if(prev_cur == NULL)
		{
			elem->next = list;
			list->prev = elem;
			list = elem;
		}
		else
		{
			elem->prev = prev_cur;
			elem->next = cur;
			prev_cur->next = elem;
			cur->prev = prev_cur;
		}
	}
}

int main()
{
	char *in_filename = new char[1000], *out_filename = new char[1000];
		
	printf("Input file: ");
	scanf("%s", in_filename);
	printf("Output file:");
	scanf("%s", out_filename);
	

	//in_filename = "input.txt";
	//out_filename = "output.txt";

	char *word = new char[1000];
	FILE *f = fopen(in_filename, "r+");
	while(fscanf(f, "%s", word) != -1)
		add(word);
	fclose(f);

	f = fopen(out_filename, "w+");
	Node *cur = list;
	while(cur != NULL)
	{
		fprintf(f, "%s\n", cur->value);
		cur = cur->next;
	}
	fclose(f);

	return 0;
}