定义为 int (*)(void*) 的函数与定义为 void* (*)(void*).您需要将 probSAT 定义为:

A function defined as int (*)(void*) is not compatible with one defined as void* (*)(void*). You need to define probSAT as:

void *probSAT(void *);

如果你想从这个函数中有效地返回一个 int，你可以返回一个全局变量的地址或者(更好的选择)为 int 分配空间并返回一个指向它的指针(并确保在加入线程时释放它).

If you want to effectively return an int from this function, you can either return the address of a global variable or (the better option) allocate space for an int and return a pointer to that (and ensure you deallocate it when you join the thread).

void *probSAT(void *param) {
    int *rval = malloc(sizeof(int));
    if (rval == NULL) {
        perror("malloc failed");
        exit(1);
    }
    ....
    *rval = {some value};
    return rval;
}


void get_thread_rval(pthread_t thread_id) 
{
    void *rval;
    int *rval_int;
    if (pthread_join(thread_id, &rval) != 0) {
        perror("pthread_join failed");
    } else {
        rval_int = rval;
        printf("thread returned %d\n", *rval_int);
        free(rval_int);
    }
}