编译运行附件中的代码,并说明程序的功能 根据自己的理解,提交不少于3张图片
程序功能:
通过thread互斥来查看两个文件中字符串的数量,一个空格分开算两个,第一个zx.txt文件先获得锁,第二个xx.txt文件则需要等待,当第一个完成之后再进行第二个文件的统计操作,最后输出总结果。
代码如下:
#include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <ctype.h> struct arg_set { char *fname; int count; }; struct arg_set *mailbox = NULL; pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER; pthread_cond_t flag = PTHREAD_COND_INITIALIZER; void *count_words(void *); int main(int argc, char *argv[]) { pthread_t t1, t2; struct arg_set args1, args2; int reports_in = 0; int total_words = 0; if ( argc != 3 ){ printf("usage: %s file1 file2\n", argv[0]); exit(1); } args1.fname = argv[1]; args1.count = 0; pthread_create(&t1, NULL, count_words, (void *) &args1); args2.fname = argv[2]; args2.count = 0; pthread_create(&t2, NULL, count_words, (void *) &args2); pthread_mutex_lock(&lock); while( reports_in < 2 ){ printf("MAIN: waiting for flag to go up\n"); pthread_cond_wait(&flag, &lock); printf("MAIN: Wow! flag was raised, I have the lock\n"); printf("%7d: %s\n", mailbox->count, mailbox->fname); total_words += mailbox->count; if ( mailbox == &args1) pthread_join(t1,NULL); if ( mailbox == &args2) pthread_join(t2,NULL); mailbox = NULL; pthread_cond_signal(&flag); reports_in++; } pthread_mutex_unlock(&lock); printf("%7d: total words\n", total_words); } void *count_words(void *a) { struct arg_set *args = a; FILE *fp; int c, prevc = '\0'; if ( (fp = fopen(args->fname, "r")) != NULL ){ while( ( c = getc(fp)) != EOF ){ if ( !isalnum(c) && isalnum(prevc) ) args->count++; prevc = c; } fclose(fp); } else perror(args->fname); printf("COUNT: waiting to get lock\n"); pthread_mutex_lock(&lock); printf("COUNT: have lock, storing data\n"); if ( mailbox != NULL ){ printf("COUNT: oops..mailbox not empty. wait for signal\n"); pthread_cond_wait(&flag,&lock); } mailbox = args; printf("COUNT: raising flag\n"); pthread_cond_signal(&flag); printf("COUNT: unlocking box\n"); pthread_mutex_unlock(&lock); return NULL; }
代码截图:
运行结果:
标签:count,thread,lock,printf,mailbox,互斥,测试,pthread,NULL From: https://www.cnblogs.com/syf0105/p/16873003.html