IO thread process -> thread synchronization mutual exclusion mechanism -> day6

目录

一、按顺序打印

1.1 函数

2.2 执行结果

二、倒置字符串

2.1 函数

2.2 执行结果

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作业

1.编写一个程序,开启3个 线程,这3个线程的ID分别为ABC,每个线程将自己的ID在屏幕上打印10 遍,要求输出结果必须按ABC的顺序显示,如ABCABC……依次递推;

        提示：Aonly wake upB,B只能唤醒C,C只能唤醒A;

2.定义一个全局变量,char str[] = "123456",要求定义两个线程：线程A, 线程B

        1). 要求A线程循环打印全局字符串str;

        2). 要求B线程循环倒置全局字符串str：将str中的内容倒置为"654321",再倒置为"123456"....

                注意：是倒置不是倒着打印

        3). 要求A线程打印出的str字符串内容为：123456或者654321.

                不允许出现乱序,例如：623451 653451,,,

        4). Ask to print upside down one at a time

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一、按顺序打印

1.1 函数

#include <stdio.h>
#include <pthread.h>
#include <string.h>
#include <unistd.h>


int flag=0;
pthread_mutex_t mutex;
pthread_cond_t cond;
pthread_t tid1,tid2,tid3;

void* A(void *arg)
{
	int i=0;
	while(i<10)
	{
		pthread_mutex_lock(&mutex);
		if(0 != flag)
		{
			pthread_cond_wait(&cond,&mutex);
		}else
		{
			flag=1;
			printf("A");
			i++;
		}

		pthread_cond_signal(&cond);
		pthread_mutex_unlock(&mutex);

	}
	pthread_exit(NULL);
}
void* B(void* arg)
{
	int i=0;
	while(i<10)
	{
		pthread_mutex_lock(&mutex);
		if(1 != flag)
		{
			pthread_cond_wait(&cond,&mutex);
		}else
		{
			flag=2;
			printf("B");
			i++;
		}
		pthread_cond_signal(&cond);
		pthread_mutex_unlock(&mutex);
	}
	pthread_exit(NULL);
}
void* C(void* arg)
{
	int i=0;
	while(i<10)
	{
		pthread_mutex_lock(&mutex);
		if(2 !=flag)
		{
			pthread_cond_wait(&cond,&mutex);
		}else
		{
			flag=0;
			printf("C\n");
			i++;
		}
		pthread_cond_signal(&cond);
		pthread_mutex_unlock(&mutex);
	}
	pthread_exit(NULL);
}


int main(int argc, const char *argv[])
{
	if(pthread_mutex_init(&mutex,NULL) !=0)
	{
		perror("pthread_mutex_init");
		return -1;
	}
	if(pthread_cond_init(&cond,NULL) != 0)
	{
		perror("pthread_cond_init");
		return -1;
	}
	if(pthread_create(&tid1,NULL,A,NULL) != 0)
	{
		perror("pthread_create");
		return -1;
	}
	if(pthread_create(&tid2,NULL,B,NULL) != 0)
	{
		perror("pthread_create");
		return -1;
	}
	if(pthread_create(&tid3,NULL,C,NULL) != 0)
	{
		perror("pthread_create");
		return -1;
	}

	pthread_join(tid1,NULL);
	pthread_join(tid2,NULL);
	pthread_join(tid3,NULL);
	pthread_mutex_destroy(&mutex);
printf("\n");

	return 0;
}//Cracked up today,不想写注释了,......

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2.2 执行结果

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二、倒置字符串

2.1 函数

#include <stdio.h>
#include <pthread.h>
#include <string.h>
#include <unistd.h>


char str[]="123456";
int flag=0;
pthread_mutex_t mutex;
pthread_cond_t cond;
pthread_t tid1,tid2;

void* dayin(void *arg)
{
	while(1)
	{
		pthread_mutex_lock(&mutex);
		if(1 != flag)
		{
			pthread_cond_wait(&cond,&mutex);
		}
		int len=strlen(str);
		char temp;
		for(int i=0;i<len/2;i++)
		{
			temp=str[i];
			str[i]=str[len-1-i];
			str[len-1-i]=temp;
		}
		flag=0;
		pthread_cond_signal(&cond);
		pthread_mutex_unlock(&mutex);

	}
	pthread_exit(NULL);
}
void* daizhi(void* arg)
{
	while(1)
	{
		pthread_mutex_lock(&mutex);
		if(0 != flag)
		{
			pthread_cond_wait(&cond,&mutex);
		}
		printf("%s\n",str);
		flag=1;
		sleep(1);
		pthread_cond_signal(&cond);
		pthread_mutex_unlock(&mutex);
	}
	pthread_exit(NULL);
}
int main(int argc, const char *argv[])
{
	if(pthread_mutex_init(&mutex,NULL) !=0)
	{
		perror("pthread_mutex_init");
		return -1;
	}
	if(pthread_cond_init(&cond,NULL) != 0)
	{
		perror("pthread_cond_init");
		return -1;
	}
	if(pthread_create(&tid1,NULL,dayin,NULL) != 0)
	{
		perror("pthread_create");
		return -1;
	}
	if(pthread_create(&tid2,NULL,daizhi,NULL) != 0)
	{
		perror("pthread_create");
		return -1;
	}

	pthread_join(tid1,NULL);
	pthread_join(tid2,NULL);
	pthread_mutex_destroy(&mutex);


	return 0;
}

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2.2 执行结果