为什么我的pthread和semaphore程序的output是空白的？

Question

The following code is written in C, and when I run the code nothing outputs to the screen. I am not coding in an IDE, so I cannot tell where the error is located. Please, any help is appreciated.

#include <pthread.h>
#include <stdio.h>
#include <semaphore.h>


int counter=0;//this is the count variable and is the variable that the treads will edit, making it the critical section
static sem_t semaphore;//this creates a pointer for our semaphore variable

void *increaseCounter();
void *decreaseCounter();

int main()
{

    sem_init(&semaphore, 0, 1);

    pthread_t t1,t2;
    pthread_create(&t1, NULL, increaseCounter, NULL);
    pthread_create(&t2, NULL, decreaseCounter, NULL);
    
    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
    sem_destroy(&semaphore);
}

void *increaseCounter()
{
    while(1)
    {
        sem_wait(&semaphore);
        counter++;
        printf("\n%d\n",counter);
        sem_post(&semaphore);
    }
}

void *decreaseCounter()
{
    while(1)
    {
        sem_wait(&semaphore);
        counter--;
        printf("\n%d\n",counter);
        sem_post(&semaphore);
    }
}

Answer 1

Run but its a loop, might gonna help you

gcc -g -Wall -o test NAME.c -lpthread

./test

#include <stdio.h>
#include <semaphore.h>
#include <pthread.h>

//this is the count variable and is the variable that 
//the treads will edit, making it the critical section
static int counter=0;
//this creates a pointer for our semaphore variable
static sem_t semaphore;

void *increaseCounter();
void *decreaseCounter();

int main()
{
    sem_init(&semaphore, 0, 1);
    pthread_t t1,t2;
    pthread_create(&t1, NULL, increaseCounter, NULL);
    pthread_create(&t2, NULL, decreaseCounter, NULL);
    
    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
    sem_destroy(&semaphore);
}

void *increaseCounter()
{
    while(1)
    {
        sem_wait(&semaphore);
        counter++;
        printf("\n%d\n",counter);
        sem_post(&semaphore);
    }
}

void *decreaseCounter()
{
    while(1)
    {
        sem_wait(&semaphore);
        counter--;
        printf("\n%d\n",counter);
        sem_post(&semaphore);
    }
}

Answer 2

You have to make a couple of changes in your code will run fine.

Always read the documentation before writing something. Here I'm attaching some documents that may help u in the future Synchronizing Threads with POSIX Semaphores .

This may improve your understanding of threadsPOSIX thread (pthread) libraries .

#include <stdio.h>
#include <semaphore.h>
#include <pthread.h>

 int counter=0;
 sem_t semaphore;
void *increaseCounter();
void *decreaseCounter();

int main()
{
    sem_init(&semaphore, 0, 1);
    pthread_t t1,t2;
    pthread_create(&t1, NULL, increaseCounter, NULL);
    pthread_create(&t2, NULL, decreaseCounter, NULL);
    
    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
    sem_destroy(&semaphore);
}

void *increaseCounter()
{
    while(1)
    {
        sem_wait(&semaphore);
        counter++;
        printf("\n%d\n",counter);
        sem_post(&semaphore);
    }
}

void *decreaseCounter()
{
    while(1)
    {
        sem_wait(&semaphore);
        counter--;
        printf("\n%d\n",counter);
        sem_post(&semaphore);
    }
}