1 /******************************************************************************* 2  * twordcount.c threaded word counter for two files 3  */ 4 #include <stdio.h> 5 #include <pthread.h> 6 #include <ctype.h> 7  8 int total_words; 9 pthread_mutex_t counter_lock=PTHREAD_MUTEX_INITIALIZER;//互斥锁10 11 int main(int argc, char* argv[]) {12   pthread_t t1, t2;13   void * count_words(void*);14   pthread_create(&t1, NULL, count_words, (void*)argv[1]);15   pthread_create(&t2, NULL, count_words, (void*)argv[2]);16   pthread_join(t1, NULL);17   pthread_join(t2, NULL);18   printf("%5d: total words \n", total_words);19 }20 21 void* count_words(void* file) {22   char* filename=(char* ) file;23   FILE* fp;24   int c, prevc=‘\0‘;25   if((fp=fopen(filename, "r"))!=NULL) {26     while((c=fgetc(fp))!=EOF) {27       if(!isalnum(c) && isalnum(prevc)) {28     pthread_mutex_lock(&counter_lock);29     total_words++;30     pthread_mutex_unlock(&counter_lock);31       }32       prevc=c;33     }34     fclose(fp);35   }else{36     perror("fopen");37   }38   return NULL;39 }