/* twordcount1.c - threaded word counter for two files. Version 1 */#include  <stdio.h>#include  <pthread.h>#include  <ctype.h>int	  total_words ;main(int ac, char *av[]){	pthread_t t1, t2;		/* two threads */	void	  *count_words(void *);	if ( ac != 3 ){		printf("usage: %s file1 file2\n", av[0]);		exit(1);	}	total_words = 0;	pthread_create(&t1, NULL, count_words, (void *) av[1]);	pthread_create(&t2, NULL, count_words, (void *) av[2]);	pthread_join(t1, NULL);	pthread_join(t2, NULL);	printf("%5d: total words\n", total_words);}void *count_words(void *f){	char *filename = (char *) f;	FILE *fp;	int  c, prevc = '\0';		if ( (fp = fopen(filename, "r")) != NULL ){		while( ( c = getc(fp)) != EOF ){			if ( !isalnum(c) && isalnum(prevc) )				total_words++;			prevc = c;		}		fclose(fp);	} else 		perror(filename);	return NULL;}