爲什麼我在這裏得到分割錯誤？

Question

#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->next_prcmd = (prcmd_t*)malloc(sizeof(prcmd_t)); 
     curNode = curNode->next_prcmd; 
    } 
    curNode->next_prcmd = node; 

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



int main() 
{ 
    if (pr_head == NULL) 
    { 
     printf("List is empty!\n"); 
    } 

    prcmd_t *pr1; 
    pr1->owner = 1; 
    pr1->burst_time = 10; 
    add_queue(pr1); 
    prcmd_t *curNode = pr_head; 
    while(curNode->next_prcmd) 
    { 
     printf("%i\n", curNode->owner); 
     curNode = curNode->next_prcmd; 
    } 
} 

編輯：

這是我現在有...

int main() 
{ 


prcmd_t *pr1; 
pr1 = (prcmd_t*)malloc(sizeof(prcmd_t)); 
pr1->owner = 1; 
pr1->burst_time = 10; 



if (pr_head == NULL) 
{ 

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

add_queue(pr1); 


prcmd_t *curNode = pr_head; 

printf("made it here 1\n"); 
while(curNode->next_prcmd) 
{ 
    printf("in the while loop\n"); 

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

輸出是： 列表是空的！ 使它這裏1

Answer 1

pr1是未初始化的指針到prcmd_t struct，解除引用初始化指針導致undefined behavior。

需要爲堆/堆棧上的結構分配空間（取決於它的會被使用），因此，一種選擇是：

// Allocate on stack 
prcmd_t pr1; 
pr1.owner = 1; 
pr1.burst_time = 10; 
add_queue(&pr1); 

和第二是：

//Allocae on heap 
prcmd_t *pr1; 
pr = (prcmd_t*)malloc(sizeof(prcmd_t)); 
pr1->owner = 1; 
pr1->burst_time = 10; 
add_queue(pr1); 

修改你的主要方法（只有主）到：

int main() 
{ 
    if (pr_head == NULL) 
    { 
     printf("List is empty!\n"); 
    } 

    prcmd_t *pr1; 
    pr1 = (prcmd_t*)malloc(sizeof(prcmd_t)); 
    pr1->owner = 1; 
    pr1->burst_time = 10; 
    add_queue(pr1); 
    prcmd_t *curNode = pr_head; 
    while(curNode && curNode->owner) 
    { 
     printf("%i\n", curNode->owner); 
     curNode = curNode->next_prcmd; 
    } 
} 

輸出

List is empty! 
1 

Answer 2

很難說沒有你tellung我們哪裏...

但

• 你必須初始化 節點 - > next_prcmd爲null
• 爲什麼你的malloc的同時，循環？你 從而destroing的電流 - >接下來， 在其下一次迭代是相當 壞...

馬里奧