多線程，互斥鎖，條件變量測試程序（未記錄後續補上）

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

static char pre=‘C’;
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
void *func(void *p)
{
while(1){
pthread_mutex_lock(&lock);
while(pre != ‘C’){
pthread_cond_wait(&cond,&lock);
}
printf(“func: A \n”);
pre = ‘A’;
pthread_cond_broadcast(&cond);
pthread_mutex_unlock(&lock);
}
return NULL;
}
void *func1(void *p)
{
while(1){
pthread_mutex_lock(&lock);
while(pre != ‘A’){
pthread_cond_wait(&cond,&lock);

}
printf("func:  B \n");
pre = 'B';

// pthread_cond_signal(&cond);
pthread_cond_broadcast(&cond);
pthread_mutex_unlock(&lock);
}

    return NULL;

}
void *func2(void *p)
{
while(1){
pthread_mutex_lock(&lock);
while(pre != ‘B’){
pthread_cond_wait(&cond,&lock);
}
printf(“func: C \n”);
pre = ‘C’;
//pthread_cond_signal(&cond);
//
pthread_cond_broadcast(&cond);
pthread_mutex_unlock(&lock);
}

return NULL;

}
int main()
{
pthread_t pid[3];
void *(*funca[3])(void )={func,func1,func2};//函數返回值類型 ( 指針變量名) (函數參數列表);
int i =0;
for(i=0;i<3;i++){
pthread_create(&pid[i],NULL,funca[i],NULL);
}
// pthread_cond_signal(&cond);
sleep(100);

return 0;

}