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c - 删除队列后显示队列的数据

问题描述

我正在使用 c 中的 struct 创建一个队列来存储客户。我可以删除客户节点，但我想显示已删除客户的信息，即姓名和条形码编号

typedef struct customer {
char name[50];          // the customer's name
double barcodeNumber;   // the barcode number from the customer's ticket
struct customer *next;  // a pointer to the next customer in the queue after this one
}
Customer;

typedef struct eventQueue {
Customer *head; // points to the customer at the front/head of the queue
Customer *tail; // points to the customer at the end/tail of the queue
} EventQueue;

这是我的删除功能

int removeCustomer(EventQueue *qPtr, Customer *c)
{


if(qPtr == NULL)
return INVALID_INPUT_PARAMETER;

if(c == NULL)
return INVALID_INPUT_PARAMETER;

if(qPtr->head == NULL)
return INVALID_QUEUE_OPERATION;


char *name;
double barcode;

strcpy(c->name,name);
barcodeCopy = c->barcode;


c=qPtr->head;
qPtr->head=qPtr->head->next;
free(c);


// Value to be returned if a function is completed successfully
return SUCCESS;
}

这是我的代码实现

void main()
{
printf("\nAttempting to remove customer from queue..");

// (attempt to) remove / pop a customer from the queue
Customer customerInfo;
 // a variable to receive the customer data removed from the queue
result = removeCustomer(pQueue, &customerInfo); // this calls your implementation of removeCustomer()

// if customer wasn't removed successfully
if (result != SUCCESS)
{
    
    printf("ERROR: Unable to remove customer from queue.\n");
}
else
{
    
    printf("..customer removed successfully!\n");

    
    printf("The customer removed was %s who was barcode number %.0lf.\n", customerInfo.name, customerInfo.barcodeNumber);}

}

标签： cpointersqueue

解决方案

只需分解 removeCustomer 方法中的操作

  1. 从队列中获取“第一/前”客户

    Customer* first = qPtr->head;

  2. 将其数据复制到您作为参数传递的客户信息结构中

    // using first for clarity but qPtr->head->name also works
    strcpy(c->name, first->name);
    c->barcodeNumber = first->barcodeNumber;

  3. 更新队列 - 移除前面

    qPtr->head = qPtr->head->next;

  4. 删除第一个客户（现已提取）

    free(first);

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