Question

我正在尝试实现一个接收List和Int作为参数的bool函数，如果列表中不存在int，则应插入int并返回true;如果已经存在，则返回false，我已经工作了几个小时使用此函数，并且if-else语句可以插入已排序的int，问题（和崩溃）是如何检查该值是否已存在并返回false，这是我的函数：结构声明

typedef struct E_Type * List;
struct E_Type
 {
  int data;
  List next = 0;
 };

和功能

bool insert(List & l, int data)
{   

   List current = l;
       do{//check if the int is already in the list
          current->data;
          current = current->next;
        //return false;
     }while (current->data == data);

      if (l == 0 || l->data > data){
              List new_list = new E_Type;
              new_list->data = data;
               new_list->next = l;
               l = new_list;
           return true;
      }

       else if(l->data < data){
             insert(l->next, data);
           return true;
     }



  }

Answer 1

do{
      //this line doesn't really do anything...
      current->data;
      //moving current forward, good.
      current = current->next;
 //If current->data is less than data in the list, it will exit the loop here anyway.
}while (current->data == data);

您也没有检查是否已到达列表的末尾。也许你想要做的就是这样：

//This is correct for for iterative approach, but I don't think this is really what you need, either...
while(current != null) {
    if (current->data == data)
        return false;
    current = current->next;
}

但是，您可能不希望使用这样的迭代来在递归函数中进行此检查，因此，只需将整个位替换为：

if (current->data == data)
   return false;

要通过递归调用返回正确的值，您需要更改：

else if(l->data < data){
     insert(l->next, data);         //Recursive call
     return true;  //you don't want to just return true, return what the recursive call returns!
}

要：

else if(l->data < data){
     return insert(l->next, data);
}

Bool对insert函数进行了排序，并检查列表中是否已存在int

1 个答案: