dict.c

来自「linux网络编程实例程序 socket程序 适合初学者。」· C语言 代码 · 共 152 行

/* dict.c - main, initw, nextin, insertw, deletew, lookupw */

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

#define	MAXWORD	50		/* maximum length of a command or word	*/
#define DICTSIZ 100		/* maximum number of entries in diction.*/
char	dict[DICTSIZ][MAXWORD+1];/* storage for a dictionary of words	*/
int	nwords = 0;		/* number of words in the dictionary	*/

int	nextin(char *cmd, char *word), initw(), insertw(const char *word);
int	deletew(const char *word), lookupw(const char *word);

/*------------------------------------------------------------------------
 * main - insert, delete, or look up words in a dictionary as specified
 *------------------------------------------------------------------------
 */
int
main(int argc, char argv[])
{
	char	word[MAXWORD+1]; /* space to hold word from input line	*/
	char	cmd;
	int	wrdlen;		/* length of input word			*/

	while (1) {
		wrdlen = nextin(&cmd, word);
		if (wrdlen < 0)
			exit(0);
		word[wrdlen] = '\0';
		switch (cmd) {
		case 'I':	/* "initialize" */
			initw();
			printf("Dictionary initialized to empty.\n");
			break;
		case 'i':	/* "insert" */
			insertw(word);
			printf("%s inserted.\n",word);
			break;
		case 'd':	/* "delete" */
			if (deletew(word))
				printf("%s deleted.\n",word);
			else
				printf("%s not found.\n",word);
			break;
		case 'l':	/* "lookup" */
			if (lookupw(word))
				printf("%s was found.\n",word);
			else
				printf("%s was not found.\n",word);
			break;
		case 'q':	/* quit */
			printf("program quits.\n");
			exit(0);
		default:	/* illegal input */
			printf("command %c invalid.\n", cmd);
			break;
		}
	}
}

/*------------------------------------------------------------------------
 * nextin - read a command and (possibly) a word from the next input line
 *------------------------------------------------------------------------
 */
int
nextin(char *cmd, char *word)
{
	int	i, ch;

	ch = getc(stdin);
	while (isspace(ch))
		ch = getc(stdin);
	if (ch == EOF)
		return -1;
	*cmd = (char) ch;
	ch = getc(stdin);
	while (isspace(ch))
		ch = getc(stdin);
	if (ch == EOF)
		return -1;
	if (ch == '\n')
		return 0;
	i = 0;
	while (!isspace(ch)) {
		if (++i > MAXWORD) {
			printf("error: word too long.\n");
			exit(1);
		}
		*word++ = ch;
		ch = getc(stdin);
	}
	return i;
}

/*------------------------------------------------------------------------
 * initw - initialize the dictionary to contain no words at all
 *------------------------------------------------------------------------
 */
int
initw()
{
	nwords = 0;
	return 1;
}

/*------------------------------------------------------------------------
 * insertw - insert a word in the dictionary
 *------------------------------------------------------------------------
 */
int
insertw(const char *word)
{
	strcpy(dict[nwords], word);
	nwords++;
	return nwords;
}

/*------------------------------------------------------------------------
 * deletew - delete a word from the dictionary
 *------------------------------------------------------------------------
 */
int
deletew(const char *word)
{
	int	i;

	for (i=0 ; i<nwords ; i++)
		if (strcmp(word, dict[i]) == 0) {
			nwords--;
			strcpy(dict[i], dict[nwords]);
			return 1;
		}
	return 0;
}

/*------------------------------------------------------------------------
 * lookupw - look up a word in the dictionary
 *------------------------------------------------------------------------
 */
int
lookupw(const char *word)
{
	int	i;

	for (i=0 ; i<nwords ; i++)
		if (strcmp(word, dict[i]) == 0)
			return 1;
	return 0;
}