2月6日 线程

1.将一个文件中的数据打印到终端上，类似一个cat函数

A进程读取文件中的数据

B进程将a读取的数据打印到终端上

文件打印完毕后，技术进程。

#include<stdio.h>

#include<sys/types.h>

#include<unistd.h>

#include<stdlib.h>

#include<sys/wait.h>

#include<pthread.h>

#include<string.h>

#include<semaphore.h>

#include<sys/stat.h>

#include<fcntl.h>

char buf[10];

sem_t sem1,sem2;

void* callBack1(void* arg)

{

intret=0;

intfd=open("./01fopen.c",O_RDONLY);

while(1){

if(sem_wait(&sem1)<0){

perror("sem_waiterror");

returnNULL;

}

ret=read(fd,buf,sizeof(buf));

if(ret==0){

break;

}

if(sem_post(&sem2)<0){

perror("sem_post");

break;

}

}

pthread_exit(NULL);

}

void* callBack2(void* arg)

{

while(1){

if(sem_wait(&sem2)<0){

perror("sem_waiterror");

returnNULL;

}

printf("%s",buf);

fflush(stdout);

if(sem_post(&sem1)<0){

perror("sem_post");

break;

}

}

}

int main(int argc, const char *argv[])

{

if(sem_init(&sem1,0,1)<0){

perror("sem_init");

return-1;

}

if(sem_init(&sem2,0,0)<0){

perror("sem_init");

return-1;

}

pthread_t tid1,tid2;

if(pthread_create(&tid1,NULL,callBack1,NULL)!=0){

fprintf(stderr,"pthread_createerror");

return-1;

}

if(pthread_create(&tid2,NULL,callBack2,NULL)!=0){

fprintf(stderr,"pthread_createerror");

return-1;

}

pthread_join(tid1,NULL);

pthread_detach(tid2);

sem_destroy(&sem1);

sem_destroy(&sem2);

return0;

}

2. 用条件变量实现，有编号ABC的三个线程，线程内分别打印自己的线程编号，要求打印书顺序为ABC,提示多个条件变量。

#include<stdio.h>

#include<sys/types.h>

#include<unistd.h>

#include<stdlib.h>

#include<sys/wait.h>

#include<pthread.h>

#include<string.h>

#include<sys/stat.h>

#include<fcntl.h>

pthread_mutex_tmutex=PTHREAD_MUTEX_INITIALIZER;

pthread_cond_tcond1=PTHREAD_COND_INITIALIZER;

pthread_cond_tcond2=PTHREAD_COND_INITIALIZER;

pthread_cond_t cond3=PTHREAD_COND_INITIALIZER;

int flag=0;

void* callback_A(void* arg)

{

while(1){

pthread_mutex_lock(&mutex);

if(flag!=0){

pthread_cond_wait(&cond1,&mutex);

}

printf("A");

flag=1;

pthread_cond_signal(&cond2);

pthread_mutex_unlock(&mutex);

}

pthread_exit(NULL);

}

void* callback_B(void* arg)

{

while(1){

pthread_mutex_lock(&mutex);

if(flag!=1){

pthread_cond_wait(&cond2,&mutex);

}

printf("B");

flag=0;

pthread_cond_signal(&cond3);

pthread_mutex_unlock(&mutex);

}

pthread_exit(NULL);

}

void* callback_C(void* arg)

{

while(1){

pthread_mutex_lock(&mutex);

if(flag!=1){

pthread_cond_wait(&cond3,&mutex);

}

printf("C");

fflush(stdout);

flag=0;

pthread_cond_signal(&cond1);

pthread_mutex_unlock(&mutex);

}

pthread_exit(NULL);

}

int main(int argc, const char *argv[])

{

pthread_ttidA,tidB,tidC;

if(pthread_create(&tidA,NULL,callback_A,NULL)){

fprintf(stderr,"pthread_createfailed\n");

return-1;

}

pthread_detach(tidA);

if(pthread_create(&tidB,NULL,callback_B,NULL)){

fprintf(stderr,"pthread_createfailed\n");

return-1;

}

pthread_detach(tidB);

if(pthread_create(&tidC,NULL,callback_C,NULL)){

fprintf(stderr,"pthread_createfailed\n");

return-1;

}

pthread_join(tidC,NULL);

pthread_mutex_destroy(&mutex);

pthread_cond_destroy(&cond1);

pthread_cond_destroy(&cond2);

pthread_cond_destroy(&cond3);

return0;

}