这是一个mergesort类型的程序。
如果你看看main中代码的最底部，当我尝试使用cin让用户输入一个整数变量＆＃34;选择＆＃34;时，我认为该程序可能从输入中得到了一些东西缓冲。我已尝试过一些东西从输入缓冲区删除任何东西，但没有任何运气来解决这个问题。该程序似乎跳过cin＆gt;＆gt;选择;好像它不在那里。
我还不完全熟悉我之前在程序中使用stringstream的方式（查找Populate函数）。我想这可能与它有关。任何见解都会非常感激。
#include "stdafx.h"
#include <string>
#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
using namespace std;
int printcount = 1;
class Node
{
public:
string retailPrice;
string wholesalePrice;
string productName;
Node * next;
Node(string ins = "", string ins1 = "", string ins2 = "") // Constructor - assigns new Links(Nodes) an empty title, and assigns the nullptr to "next"
//indicating that there is no data stored in the following node i.e. "tail"
{
productName = ins;
retailPrice = ins1;
wholesalePrice = ins2;
next = nullptr;
}
};
class List
{
public:
Node * productList; // "productList" is the address of the first node in the list.
List() { productList = nullptr; } // constructor - makes the address of the first node "productList" nullptr i.e. "head"
bool IsEmpty() //If the address of the first node "theList" is null, returns true
{
return (productList == nullptr) ? true : false;
}
void Add(string ins, string ins1, string ins2) //this function adds a new node to the beginning of the linked list.
{
/* Node * Node1 = productList; //Ask bob why this doesn't work
while (Node1->next != nullptr) //searches for tail
{
Node1 = Node1->next; //Node1 points to the following node
}
Node * temp = new Node(ins); //Creates a new Node;
Node1->next = temp; //assigns the old tail to point to the new node
*/
Node * oldFirst = productList; //initializies pointer "oldFirst" to point to the current address of the first node, "productList"
productList = new Node(ins, ins1, ins2); // creates a new node on the heap with string passed to Add function
// theList is now the address of this new node.
productList->next = oldFirst; // the new header "productList"
}
void Remove(Node * thisOne)
{
Node * guyBefore = FindTheGuyBefore(thisOne);
guyBefore = thisOne->next; //assigns the "next" address of node preceding node to be deleted, to the address of the node following
// the node to be deleted.
thisOne->next = nullptr;
}
int Populate()
{
//cin.ignore();
string input;
int count = 0;
while (getline(cin, input))
{
stringstream ss(input);
getline(ss, input, ',');
string s = input; //name of product
ss >> ws;
getline(ss, input, ',');
string s1 = input; //retail price
ss >> ws;
getline(ss, input);
string s2 = input; //wholesale price
count++;
Add(s, s1, s2);
}
/*
char buffer[120];
string buf(buffer);
int count = 0;
while (getline(cin, buf))
{
Add(buf);
count++;
}
*/
return count;
}
void Visit(void(*fp)(string s, string s1, string s2)) //visits all nodes and applies a void function to a string
{
int count1 = 0;
Node * currentNode = productList; //assigns 'curLink' the address of 'theList'
while (currentNode != nullptr) //loop goes until it reaches the tail of the linked list
{
(*fp)(currentNode->retailPrice, currentNode->wholesalePrice, currentNode->productName); //applies the function to the title of the node
currentNode = currentNode->next; //assigns address of 'curLink' the address of the following node
++count1;
}
}
void MergeSort(int select)
{
if (productList == nullptr) return; // if the list is empty, terminate the function (sort unnecessary)
if (productList->next == nullptr) return; // if there is only one item in the list, terminate the function (sort unnecessary)
List list1; // Instantiate two lists
List list2;
Split(list1, list2); // This should leave productList == nullptr. Splits theList into two lists.
list1.MergeSort(select); // Performs the MergeSort operation
list2.MergeSort(select);
Merge(list1, list2, select);
}
private:
Node * FindTheGuyBefore(Node * thisOne)
{
Node * aNode = productList; //aLink points to productList, the address of the first node
while (aNode->next != thisOne) //looks through the list until the address stored in "next" is the address of the value
//preceding 'thisOne', assigns aLink the value of that address
aNode = aNode->next;
return aNode;
}
Node * GetHeadNode() //returns the address of the head of the linked list
{
Node * answer = productList; //answer holds the address of theList
if (answer != nullptr) //if the address of theList is not a null pointer
{
productList = answer->next; //theList is now the address of the following node
answer->next = nullptr; //answer points to the nullptr
}
return answer;
}
void Push(Node * new1) //inserts a node at the beginning of the linked list
{
if (new1 == nullptr) return; // nothing to add
new1->next = productList; // the address pointed to by new1 is the address of the head
productList = new1; // new1 is now the head
}
void Split(List & list1, List & list2) //inserts null pointers between items in a list
{
Node * cur0 = nullptr;
bool left = true;
while (productList != nullptr)
{
cur0 = GetHeadNode(); //cur0 is the head of the linked list
if (left) // Add cur0 link to the start of list1
{
list1.Push(cur0); //inserts a node where the value of next is nullptr; essentially splitting the list
left = false;
}
else // Add cur0 link to the start of list2
{
list2.Push(cur0);
left = true;
}
}
}
Node * GetSmaller(List & otherList, int select)
{ // Will extra smaller head node from this List or otherList
Node * head1 = productList;
Node * head2 = otherList.productList;
if (head1 == nullptr) return otherList.GetHeadNode();
if (head2 == nullptr) return GetHeadNode();
if (select == 1)
{
if ((head1->productName) < (head2->productName)) return GetHeadNode();
}
else if (select == 2)
{
if ((head1->retailPrice) < (head2->retailPrice)) return GetHeadNode();
}
else if (select == 3)
{
if ((head1->wholesalePrice) < (head2->wholesalePrice)) return GetHeadNode();
}
return otherList.GetHeadNode();
}
void Merge(List & list1, List & list2, int select)
{// Assumes productList == nullptr
Node * new1 = list1.GetSmaller(list2, select);
productList = new1; // First guy in list or nullptr
Node * cur0 = productList; // this must point to last elt added to theList (empty due to split)
while ((new1 = list1.GetSmaller(list2, select)) != nullptr)
{
cur0->next = new1;
new1->next = nullptr;
cur0 = new1;
}
}
};
void print(string s, string s1, string s2)
{
cout << "Product # " << printcount << endl;
cout << left << setw(20) << "Product Name: " << left << setw(20) << s2 << endl;
cout << left << setw(20) << "Retail Price: " << left << setw(20) << s << endl;
cout << left << setw(20) << "Wholesale Price: " << left << setw(20) << s1 << endl << endl;
++printcount;
};
int main()
{
List myProductList;
cout << "****************************************************************************************************" << endl
<< " PROGRAM FOR SORTING INVENTORY BY PRODUCT NAME, RETAIL PRICE, OR WHOLESALE PRICE " << endl
<< "****************************************************************************************************" << endl << endl;
//POPULATE THE LIST
cout << "Enter the name, retail price, and wholesale price of a product in that order, seperated by commas." << endl;
cout << "You may enter multiple products. Seperate each product with a return. When you have finished entering items, enter CTRL-Z. " << endl << endl;
myProductList.Populate();
cout << "Would you like to:" << endl << endl;
cout << "1. Display your list." << endl;
cout << "2. Sort your list." << endl;
cout << "3. Add an item to your list." << endl;
cout << "4. Delete an item from your list." << endl;
cout << "5. Modify an item on your list." << endl;
cout << "6. Determine whether your list is empty." << endl << endl << "Enter an integer." << endl << endl;
int select;
cin >> select;
system("Pause");
return 0;
}
答案 0 :(得分：0)
输入Ctrl + Z结束Populate中的循环后，输入流将处于文件结束状态，任何进一步的输入尝试都将失败。
因此，cin >> select;中的cin不会尝试阅读任何内容，因为class tableData
{
private $row1 = array("Kalle1", "address1", "postal code1", "1@email.se", "070111001", "08111001");
private $row2 = array("kalle2", "address2", "postcode2", "2@email.se", "070111002", "08111002");
private $row3 = array("kalle3", "address3", "postcode3", "3@email.se", "070111003", "08111003");
private $row4 = array("kalle4", "address4", "postcode4", "4@email.se", "070111004", "08111004");
private $rader;
public function __construct() {
$this->rader = array(
array($this->row1),
array($this->row2),
array($this->row3),
array($this->row4)
);
}
报告已经到达输入结束。