c - C 结构体中的函数指针

Question

当我尝试在结构内部使用 C 函数指针时遇到错误(该函数只是从链接列表中弹出第一个元素并返回该元素):

main.c: In function ‘simulation’: main.c:279: error: incompatible types when assigning to type ‘struct PROCESS *’ from type ‘PROCESS’

我的代码是这样的:

typedef struct PROCESS {
    struct PS_TABLE *tbl_ref;
    int pid;
    int time_in_prev_state;
    int state_ts;
    int static_prio;
    int dynamic_prio;
    int cpu_rem;            
    struct PROCESS *next;
} PROCESS;

typedef void (*Add) (PROCESS *head, PROCESS *new_ps);
typedef PROCESS (*Get) (PROCESS *head);

typedef struct SCHEDULER {
    int quantum;
    sched_t sch_alg;
    Add add_process;
    Get get_next_process;
} SCHEDULER;

PROCESS *fcfs_get_next_proc(PROCESS **head) {     //POP
    PROCESS *tmp = head;
    head = tmp->next;
    tmp->next = NULL;
    return tmp;
}

SCHEDULER *scheduler_obj = malloc(sizeof(SCHEDULER));
scheduler_obj->get_next_process = fcfs_get_next_proc;

PROCESS *RUNNING_PROCESS = NULL;
RUNNING_PROCESS = scheduler->get_next_process(head_proc);

任何帮助将不胜感激!

Answer 1

您的 next 结构字段是一个 struct PROCESS *，并且您的函数返回一个 PROCESS。让它们的类型相同就可以了。

typedef struct PROCESS *(*Get) (PROCESS *head);
typedef PROCESS *(*Get) (PROCESS *head);