在2个线程之间交替(Alternate between 2 threads)

 我想制作一个程序，用2个函数写入1到100之间的奇数和偶数，第一个函数打印前5个奇数，第二个函数打印前5个偶数，然后再返回第一个函数进行打印第二个5个奇数等等。 在这个程序中，我想在2线程之间交替，但我找不到解决方案。 这是我的代码，在这段代码中我创建了40线程。有谁知道如何在2个线程之间进行交替并找到相同的输出。 
 
#include<stdio.h>
#include<pthread.h>
pthread_t tid[40];
int pair=2;
int impair=1 ;
pthread_mutex_t lock;

void* genpair(void *arg)
{
    pthread_mutex_lock(&lock);
    int i = 0;
    for (i=0 ; i<5 ; i++,pair+=2)
    {
        printf("%d ",pair) ;
    }
printf("  ");    
pthread_mutex_unlock(&lock);

    return NULL;
}
void* genimpair(void *arg)
{
    pthread_mutex_lock(&lock);
    int i = 0;
    for (i=0 ; i<5 ; i++,impair+=2)
    {
         printf("%d ",impair) ;
    }
printf("  ");    
pthread_mutex_unlock(&lock);

    return NULL;
}

int main(void)
{
    int i = 0;
    int j=0 ;
    int err;

    if (pthread_mutex_init(&lock, NULL) != 0)
    {
        printf("\n mutex init failed\n");
        return 1;
    }

    for(j=0 ; j<20 ; j+=2)  
    {
        pthread_create(&(tid[j]), NULL, &genpair, NULL);
        pthread_create(&(tid[j+1]), NULL, &genimpair, NULL);
        pthread_join(tid[j], NULL);
        pthread_join(tid[j+1], NULL);           
    }

    pthread_mutex_destroy(&lock);

    return 0;
}

I wanted to make a program that writes the odd and even numbers between 1 and 100 with 2 functions , the first function prints the first 5 odd numbers , the second function prints the first 5 even numbers and again we return to the first function to print the second 5 odd numbers and so on . In this program i wanted to alternate between only 2 threads , but i can't find the solution . Here's my code , in this code i created 40 threads.Does anyone knows how to alternate between 2 threads and find the same output.
 
#include<stdio.h>
#include<pthread.h>
pthread_t tid[40];
int pair=2;
int impair=1 ;
pthread_mutex_t lock;

void* genpair(void *arg)
{
    pthread_mutex_lock(&lock);
    int i = 0;
    for (i=0 ; i<5 ; i++,pair+=2)
    {
        printf("%d ",pair) ;
    }
printf("  ");    
pthread_mutex_unlock(&lock);

    return NULL;
}
void* genimpair(void *arg)
{
    pthread_mutex_lock(&lock);
    int i = 0;
    for (i=0 ; i<5 ; i++,impair+=2)
    {
         printf("%d ",impair) ;
    }
printf("  ");    
pthread_mutex_unlock(&lock);

    return NULL;
}

int main(void)
{
    int i = 0;
    int j=0 ;
    int err;

    if (pthread_mutex_init(&lock, NULL) != 0)
    {
        printf("\n mutex init failed\n");
        return 1;
    }

    for(j=0 ; j<20 ; j+=2)  
    {
        pthread_create(&(tid[j]), NULL, &genpair, NULL);
        pthread_create(&(tid[j+1]), NULL, &genimpair, NULL);
        pthread_join(tid[j], NULL);
        pthread_join(tid[j+1], NULL);           
    }

    pthread_mutex_destroy(&lock);

    return 0;
}

原文：https://stackoverflow.com/questions/33423221