Question

我收到了这个错误。请帮忙！

3.c：在函数main中：

3.c：92：错误：从类型prcmd_t分配类型struct prcmd_t *时出现不兼容的类型

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

typedef struct pr_struct{
        int owner;
        int burst_time;
        struct pr_struct *next_prcmd;
} prcmd_t;
static prcmd_t *pr_head = NULL;
static prcmd_t *pr_tail = NULL;
static int pending_request = 0;
static pthread_mutex_t prmutex = PTHREAD_MUTEX_INITIALIZER;


int add_queue(prcmd_t *node)
{       pthread_mutex_lock(&prmutex);
        //code
        prcmd_t *curNode = pr_head;
        if(pr_head == NULL) { pr_head = node; return;}
        while(curNode->next_prcmd)
        {
              curNode = curNode->next_prcmd;
        }
        curNode->next_prcmd = node;

        //
        pending_request++;
        pthread_mutex_unlock(&prmutex);
        return(0);
}

**//inprogress
int remove_queue(prcmd_t **node)
{
    printf("prenull");
    pthread_mutex_lock(&prmutex);
    prcmd_t *tempNode;
    if(node == NULL)
    {
        //your code
        printf("Queue is empty");
        //
        pthread_mutex_unlock(&prmutex);
        return(-1);
    }
    else
    {
    printf("in else");
        //your code
        tempNode =(*node)->next_prcmd;
        free(node);
        //
        pending_request--;
        pthread_mutex_unlock(&prmutex);
        return(0);
    }
}
//end progress**


int main()
{

    if (pr_head == NULL)
    {

        printf("List is empty!\n\n");
    }

    int i=0;
    int length = 4;
    prcmd_t *pr[length];
    for(i =0;i<length;i++)
    {
        pr[i] = (prcmd_t*)malloc(sizeof(prcmd_t));
        pr[i]->owner = i+1;
        pr[i]->burst_time = i + 2;
        add_queue(pr[i]);
    }


    prcmd_t *curNode = pr_head;

    while(curNode)
    {
        printf("%i  %i\n", curNode->owner,curNode->burst_time);
        curNode = curNode->next_prcmd;
    }
**//something is messed up here i think.
    curNode = *pr_head;
    remove_queue(&curNode);
//**

    while(curNode)
    {
        printf("%i  %i\n", curNode->owner,curNode->burst_time);
        curNode = curNode->next_prcmd;
    }
}

Answer 1

curNode的类型为prcmd_t *（指向prcmd_t的指针），而pr_head的类型为prcmd_t *，因此它们处于相同的引用级别，但您尝试分配值由pr_head（类型为prcmd_t）指向curNode（类型为prcmd_t *），这是不兼容的。

我不清楚你要做什么，但正确的语法是

curNode = pr_head;

或

memcpy(curNode, pr_head, sizeof(prcmd_t));

具有指针和链表删除功能的不兼容类型

1 个答案: