在C中重载比较运算符导致“无效运算符<”

@H_419_1@目前正在尝试使用C对每个对象包含字符串的对象矢量进行排序

字符串可以包含字母或数字(由于设计约束,这是必要的,因为比较器可以更改).

此时,对象的类被重载,因此当比较两个对象时,将比较它们包含的字符串.这是有用的 – 然而,当我使用排序操作(例如STL排序)按顺序放置对象时,它将按顺序排序三个字符串,如“1”,“4”,“12” “1”,“12”,“4”. 4大于12,但因为它从最左边的数字开始比较,所以发生这种“不正确”排序.

我最初的反应是改变比较操作的重载方式.我首先检查我正在比较的字符串的长度 – 如果字符串的内容大或小,这将是一个明显的标志.

// overloaded comparision operators
friend bool operator<(const nodeRecord & record1,const nodeRecord & record2){
    // we need to deal with Strings of different lengths...
    if(record1.comparator.length() < record2.comparator.length())
        return true;
    else
        return (record1.comparator < record2.comparator);
}

此操作导致“表达式：无效运算符<”运行时的消息. 关于我犯错误的任何想法？似乎我应该能够准确地指示操作如何进行排序操作 – 即使它是无效的,因为我当前正在使用向量来包含对象. 初始化nodeRecord对象时的比较器：

nodeRecord(int fromNode,int toNode,int connectionCost,bool compareByCost = falsE){
    // take the provided stock information and insert it into the object
    Stringstream fromNodeSS;
    fromNodeSS << fromNode;
    this->fromNode = fromNodeSs.str();
    Stringstream toNodeSS;
    toNodeSS << toNode;
    this->toNode = toNodeSs.str();
    this->connectionCost = connectionCost;

    // set the comparator to our chosen comparision term
    if (!compareByCost){
        this->comparator = this->fromNode; // we use from node in this case,since we build the tree outWARDs
    }
    else{
        Stringstream ss;
        ss << this->connectionCost;
        this->comparator = ss.str(); // we use the connection cost in this case,to allow us to sort new connections
    }

    // set this as a non-null (activE) record
    this->nullRecord = false;
}

bool compare(std::string const& lhs,std::string const& rhs) {
  if (lhs.length() < rhs.length()) { return true; }
  if (rhs.length() < lhs.length()) { return false; } // don't forget this
  return lhs < rhs;
}