我想知道如何在类toString()的链接列表中调用BoxClass方法。 BoxClass具有double length，width和height。
我的BoxClass:
class BoxClass{
private:
double length;
double width;
double height;
public:
// Default constructor w/ no parameters
BoxClass(){
length = 0;
width = 0;
height = 0;
}
// Constructor with arguments
BoxClass(double boxLength, double boxWidth, double boxHeight){
length = boxLength;
width = boxWidth;
height = boxHeight;
}
// Setters and Getters
void setLength(double boxLength){
length = boxLength;
}
double getLength(){
return length;
}
void setWidth(double boxWidth){
width = boxWidth;
}
double getWidth(){
return width;
}
void setHeight(double boxHeight){
height = boxHeight;
}
double getHeight(){
return height;
}
// Returns the volume of the boxes
double Volume(){
return (length * width * height);
}
// toString method for boxes, returns "(length) x (width) x (height) string
string toString(){
return ("(" + to_string(length)+ "x" + to_string(width) + "x" + to_string(height) + ")");
}
}; // End of BoxClass() class
LinkNode.h
//Template ListNode class definition.
#ifndef LINKNODE_H
#define LINKNODE_H
template <typename T> class LinkList;
template <typename T> class LinkNode{
friend class LinkNode <T>;
public:
LinkNode(const T &);
T getData()const;
T data;
LinkNode <T> *nextPtr;
};
template <typename T> LinkNode <T>::LinkNode(const T &info):data(info), nextPtr(NULL){
// Empty body
}
template <typename T>T LinkNode<T>::getData()const{
return data;
}
#endif
Main(创建类，将其添加到链接列表
// Create the Box class
BoxClass userBox(length, width, height);
// Add box class to Link List
Box.insertNode(userBox);
Box.print();
LinkList.h print()方法
template<typename T>void LinkList<T>::print()const {
// To list off nodes
int counter = 1;
if (isEmpty()) {
cout << "No boxes in list!\n";
} else {
LinkNode<T>*currentPtr = firstPtr;
cout << "Your boxes in increasing order of volume is:\n";
// while (currentPtr) {
while (currentPtr != NULL) {
// Output as "#. (length x width x height)
cout << counter << ". " << currentPtr->data << endl;
printf(" %i. %.2f\n", counter, currentPtr->data);
currentPtr = currentPtr->nextPtr;
counter++;
}
}
}
LinkList.h
//Template LinkList class definition.
#ifndef LINKLIST_H
#define LINKLIST_H
#include <iostream>
#include "LinkNode.h"
using namespace std;
template<typename T> class LinkList {
public:
LinkList();
void addNode(const T &);
void insertNode(const T &);
bool isEmpty() const;
void print() const;
private:
LinkNode<T>*firstPtr;
LinkNode<T>*getNewNode(const T &);
};
template<typename T>LinkList<T>::LinkList() :firstPtr(NULL) {
// Empty body
}
template <typename T>void LinkList<T>::insertNode(const T &value) {
LinkNode<T>*newPtr = getNewNode(value);
bool inserted = false;
if (isEmpty() || (newPtr->data < firstPtr->data)) {
newPtr->nextPtr = firstPtr;
firstPtr = newPtr;
// cout << " " << newPtr->data << " inserted at front of list.\n";
printf(" %.2f inserted at front of list.\n", newPtr->data);
} else {
LinkNode<T>*currentPtr = firstPtr;
while (currentPtr->nextPtr && !inserted) {
if (newPtr->data < currentPtr->nextPtr->data) {
// cout << " " << newPtr->data << " inserted before " << currentPtr->nextPtr->data << ". " << endl;
printf(" %.2f inserted before %.2f.\n", newPtr->data, currentPtr->nextPtr->data);
newPtr->nextPtr = currentPtr->nextPtr;
currentPtr->nextPtr = newPtr;
inserted = true;
} else {
currentPtr = currentPtr->nextPtr;
}
}
if (!inserted) {
currentPtr->nextPtr = newPtr;
printf(" %.2f inserted at the end of list.\n", newPtr->data);
}
}
}
template<typename T>bool LinkList<T>::isEmpty()const {
return firstPtr == NULL;
}
template<typename T>LinkNode<T>*LinkList<T>::getNewNode(const T &value) {
return new LinkNode<T>(value);
}
template<typename T>void LinkList<T>::print()const {
// To list off nodes
int counter = 1;
if (isEmpty()) {
cout << "No boxes in list!\n";
} else {
LinkNode<T>*currentPtr = firstPtr;
cout << "Your boxes in increasing order of volume is:\n";
// while (currentPtr) {
while (currentPtr != NULL) {
// Output as "#. (length x width x height)
cout << counter << ". " << currentPtr->data << endl;
printf(" %i. %.2f\n", counter, currentPtr->data);
currentPtr = currentPtr->nextPtr;
counter++;
}
}
}
#endif
再次，我的问题是-如何遍历列表并调用
toString() BoxClass方法？我尝试了cout << data.toString() << endl;的所有操作，但不起作用。我已经坚持了好几天，有人可以帮我吗？编辑:添加了LinkList.h
最佳答案
问题在于，您的LinkList<T>类的实现无法让客户端代码在循环中遍历列表的每个节点。如果我们不想打印，但每个盒子都做了其他事情怎么办？
另外，如果我有一个LinkList<Widget>，这看起来会很奇怪，当我调用print()时，我会看到文本:
“您的盒子按升序排列是:”;
我会说:“什么盒子？什么体积？我有小部件，而不是盒子”。
更完整的实现应如下所示(注意:尚未编译。它旨在为您提供应做的要旨):
template<typename T> class LinkList {
public:
LinkList();
void addNode(const T &);
void insertNode(const T &);
bool isEmpty() const;
// this is what you're missing from the current implementation
typedef LinkNode<T>* Iterator;
Iterator begin() { return firstPtr; }
Iterator next(Iterator ptr) { return ptr->nextPtr; }
Iterator end() { return NULL; }
private:
LinkNode<T>* firstPtr;
LinkNode<T>* getNewNode(const T &);
};
然后，此
print函数不必成为链接列表的一部分。它可以生活在外面:LinkList<BoxClass> boxList;
//...
void print()
{
if (boxList.isEmpty())
cout << "No boxes in list!\n";
else
{
int counter = 1;
cout << "Your boxes in increasing order of volume is:\n";
// get first box
LinkList<BoxClass>::Iterator curBox = boxList.begin();
// loop until no more boxes
while (curBox != boxList.end())
{
// now use curBox to do whatever you want with this box
BoxClass& b = curBox->getData();
cout << counter << ". " << b.toString();
// go to the next box
curBox = boxList.next(curBox);
counter++;
}
}
}
注意
print如何不再是LinkList的成员。另外，请注意typedef，以便为客户端使用的LinkNode指针提供“好”的名称。评论应不言自明。我不想通过引入“真正的”迭代器(即重载的
++)来使代码过于复杂，但是该运算符将替换LinkList<T>:::next()函数调用。我将其留给您作为其他练习。