c++ - 重载比较运算符不工作

Question

我正在尝试比较我的类 CustomerNode 的两个对象，然后返回与这些方法的字母顺序优势相关的结果。我无法弄清楚为什么这不起作用。对我来说，逻辑似乎不错，我正在按照作业中的说明进行操作。

    bool OrderedList::add (CustomerNode* newEntry)
{
if (newEntry != 0)
{
    CustomerNode * current;
    CustomerNode * previous = NULL;
    if(!head)
        head = newEntry;
    current = head;
  // initialize "current" & "previous" pointers for list traversal
   while(current && *newEntry < *current) // location not yet found (use short-circuit evaluation)
   {
    // move on to next location to check
    previous = current;
    current = current->getNext();
   }

  // insert node at found location (2 cases: at head or not at head)
  //if previous did not acquire a value, then the newEntry was
  //superior to the first in the list. 
  if(previous == NULL)
    head = newEntry;
  else
  {
    previous->setNext(newEntry); //Previous now needs to point to the newEntry
    newEntry->setNext(current); //and the newEntry points to the value stored in current.
  }
}
    return newEntry != 0;  // success or failure
    }

好的，这是程序中包含的重载运算符<，在通用对象上测试它会得到预期的结果:

    bool CustomerNode::operator< (const CustomerNode& op2) const
    {
       bool result = true;
       //Variable to carry & return result
       //Initialize to true, and then:
       if (strcmp(op2.lastName, lastName))
        result = false;

        return result;
       }

我是编程的新手，所以我很感激任何回复，尤其是风格评论，因为我还在学习。我的逻辑是错误的，还是我需要注意其他规则？我不完全理解为什么我的参数是引用，或者我是否真的需要取消引用参数来调用运算符。

谢谢。

Answer 1

你的条件是错误的:

if (strcmp(op2.lastName, lastName))

对于不同的字符串，无论它们的顺序如何，这将返回 not-false (true)，而您的函数将返回 false。

正确的条件是:

if (strcmp(op2.lastName, lastName) >= 0)

或者你可以重写整个东西:

bool CustomerNode::operator< (const CustomerNode& op2) const
{
   return  strcmp(op2.lastName, lastName) < 0;
}