我编写了以下函数来从文件中读取并在Visual Studio 2015中将“记录”加载到BST中。它的工作方式与我在Windows中的预期相同但是当我在mac上运行该函数时，它会导致无限循环。我无法弄清楚为什么。有人可以对此有所了解。使用完整代码更新，问题在于以下功能：
BinarySearchTree readFile()
{
ifstream myfile;
myfile.open("character.txt");
string name;
string aString = "Empty";
BinarySearchTree loadTree;
List list1;
int index = 1;
bool finishRecord = false;
if (!myfile.peek() == myfile.eof())
{
while (!myfile.eof())
{
getline(myfile, name);
while (!finishRecord)
{
getline(myfile, aString);
if (aString == "/")
{
finishRecord = true;
}
else
{
list1.insert(index, aString);
index += 1;
}
}
KeyedItem an_item(name, list1, true);
loadTree.searchTreeInsert(an_item);
//reset variables used for each record
index = 1;
list1.removeAll();
finishRecord = false;
}
}
myfile.close();
return loadTree;
} // end readFile
完整代码：
#include <iostream> //needed for input and output and the console screen
#include <fstream> //needed to read/write a file
#include <iomanip>
#include <algorithm> //needed to use the transform function
#include "ListP.h" //linked list class
#include "BST.h" // binary tree operations
using namespace std;
string suspectsArray[256]; //array of the suspects
int suspectIndex = 0;
KeyedItem ADD();
BinarySearchTree readFile();
void QUIT(BinarySearchTree& passedTree, string addedItems[], int arrayIndex);
bool withinTree(BinarySearchTree& passedTree, string name);
string INQUIRY(BinarySearchTree& passedTree);
void suspects(TreeItemType& anItem);
void findTip(BinarySearchTree& passedTree, string tip, int &noSuspects);
int main()
{
string aString;
BinarySearchTree characterTree = readFile();
KeyedItem an_Item;
string addedItems[256] = {};
int index = 0;
string answer;
string inquiryReturn = "";
bool main = false;
bool inTree = false;
while (!main)
{
cout << "WE ARE AT MAIN LOOP. YOU CAN ADD, INQUIRY, OR QUIT";
cout << endl;
if (inquiryReturn == "")
{
cin >> answer;
cin.ignore(); //need to flush the input for the getline()
}
else
{
inquiryReturn = "";
}
//since we need to accept the input regardless of it case
//so going to make the input into lower case
transform(answer.begin(), answer.end(), answer.begin(), tolower);
//determine which operation the user called
if (answer == "add") //user wishes to ADD a character
{
cout << endl;
an_Item = ADD();
//need to determine if the record for the character
//is already in the tree or not
inTree = withinTree(characterTree, an_Item.getKey());
if (!inTree)
{
addedItems[index] = an_Item.getKey();
index += 1;
characterTree.searchTreeInsert(an_Item);
}
else
{
cout << "Character already in tree." << endl;
}
inTree = false;
}
else if (answer == "inquiry") //user wishes to do an INQUIRY
{
cout << "User wants to do an INQUIRY" << endl;
characterTree.postorderTraverse(suspects);
inquiryReturn = INQUIRY(characterTree);
answer = inquiryReturn;
suspectIndex = 0;
}
else if (answer == "quit") //user wishes to QUIT the program
{
if (index > 0) //if the user added a character, save
{
cout << "OK, saving database to file "
"\"character.txt\" ";
QUIT(characterTree, addedItems, index);
cout << "... Done. Goodbye." << endl;
main = true;
}
else
{
cout << "OK, saving database to file "
"\"character.txt\" ";
cout << "... Done. Goodbye." << endl;
main = true;
}
}
else
{
cout << "You didn't enter a valid command." << endl;
}
}
return 0;
} //end main
void suspects(TreeItemType& anItem)
{
suspectsArray[suspectIndex] = anItem.getKey();
suspectIndex++;
}
//Function to get a record to add to the binary search tree
//gets the record in the type KeyedItem
KeyedItem ADD()
{
string name;
string a_string;
List list1;
int index = 1;
bool end = false;
cout << "OK, we are now adding a character to the database."
<< endl;
cout << "Name of Character:" << setw(5) << " ";
getline(cin, name);
cout << "Attributes:" << setw(12) << " ";
//loop to get attributes if any
while (!end)
{
getline(cin, a_string);
if (a_string == "")
{
//if no attributes were added, need to prompt for one
if (list1.getLength() == 0)
{
cout << "Need to enter at least one attribute." <<
endl << setw(23) << " ";
}
else
{
cout << endl;
end = true;
}
}
else
{
list1.insert(index, a_string);
index += 1;
cout << setw(23) << " ";
}
}
KeyedItem an_item1(name, list1, true);
return an_item1;
} // end ADD
//Function to read the database file and
//load all of the records into a Binary Search Tree.
BinarySearchTree readFile()
{
ifstream myfile;
myfile.open("character.txt");
string name;
string aString = "Empty";
BinarySearchTree loadTree;
List list1;
int index = 1;
bool finishRecord = false;
if (!myfile.peek() == myfile.eof())
{
while (!myfile.eof())
{
getline(myfile, name);
while (!finishRecord)
{
getline(myfile, aString);
if (aString == "/")
{
finishRecord = true;
}
else
{
list1.insert(index, aString);
index += 1;
}
}
KeyedItem an_item(name, list1, true);
loadTree.searchTreeInsert(an_item);
//reset variables used for each record
index = 1;
list1.removeAll();
finishRecord = false;
}
}
myfile.close();
return loadTree;
} // end readFile
//Function to run if additional shady characters were manually added to the Binary Search Tree
//It should the added characters to the database text file.
void QUIT(BinarySearchTree& passedTree, string addedItems[], int arrayIndex)
{
ofstream outfile; //variable that will be assigned to the file
KeyedItem an_item; //record that needs to be added to file
string aString;
outfile.open("character.txt", ios::app);
if (outfile.is_open())
{
for (int i = 0; i < arrayIndex; i++)
{
passedTree.searchTreeRetrieve(addedItems[i], an_item);
outfile << an_item.getKey() << "\n";
int jkl = an_item.attributes.getLength();
for (int bnm = 1; bnm < jkl + 1; bnm++)
{
an_item.attributes.retrieve(bnm, aString);
outfile << aString << "\n";
}
outfile << "/\n";
}
outfile.close();
}
} // end QUIT
//function to check whether or not the character is already in the tree
bool withinTree(BinarySearchTree& passedTree, string name)
{
KeyedItem item;
try
{
passedTree.searchTreeRetrieve(name, item);
}
catch (TreeException& error)
{
//the character is not within the tree
return false;
}
//the character is within the tree
return true;
} // end withinTree
//Function to if the tip matches any of the attributes of the suspects
void findTip(BinarySearchTree& passedTree, string tip,int &noSuspects)
{
KeyedItem aItem;
bool tipFound = false;
string aString;
//look at each of the characters attributes
//to see if they are a match for the tip
for (int asd = 0; asd < suspectIndex; asd++)
{
tipFound = false;
if (suspectsArray[asd] != "")
{
passedTree.searchTreeRetrieve(suspectsArray[asd], aItem);
//goes through each of the attributes of a character
for (int iop = 1; iop < aItem.attributes.getLength() + 1; iop++)
{
aItem.attributes.retrieve(iop, aString);
transform(aString.begin(), aString.end(), aString.begin(), toupper);
if (aString == tip)
{
tipFound = true;
}
}
//if none of character's attribute match
//remove them from the suspectArray
if (tipFound == false)
{
suspectsArray[asd] = "";
noSuspects -= 1;
}
}
}
} // end findTIP
//Function to find the perpetrator, if any
string INQUIRY(BinarySearchTree& passedTree)
{
string codeName; //string variable for inquiry code name
string command; //string variable for command input
string aString;
string checkSuspect;
int noSuspects = suspectIndex;
bool tipFound = false;
cout << "OK, we are now conducting an inquiry." << endl;
cout << endl << "Enter a Code Name for this Inquiry:";
cout << setw(5) << " ";
getline(cin, codeName);
while (command != "ADD" && command != "QUIT" && command != "INQUIRY")
{
cout << "What would you like to do?" << endl;
getline(cin, command);
transform(command.begin(), command.end(), command.begin(), toupper);
if (command == "TIP")
{
cout << "Enter Tip Info:" << setw(25) << " ";
getline(cin, command);
transform(command.begin(), command.end(), command.begin(), toupper);
findTip(passedTree, command, noSuspects);
//if there's only 1 suspect left, alert the user
if (noSuspects == 1)
{
cout << "ALERT! That leaves only one \n"
<< "suspect in the " << codeName << " inquiry:"
<< setw(13) << " ";
for (int k = 0; k < suspectIndex; k++)
{
if (suspectsArray[k] != "")
{
cout << suspectsArray[k] << endl;
}
}
}
else if (noSuspects == 0) //all suspects have been eliminated
{
cout << "There no suspects that are match." << endl;
}
}
else if (command == "CHECK")
{
bool found = false;
cout << "Enter Name of character:" << setw(16) << " ";
getline(cin, checkSuspect);
transform(checkSuspect.begin(), checkSuspect.end(),
checkSuspect.begin(), toupper);
for (int p = 0; p < suspectIndex; p++)
{
aString = suspectsArray[p];
transform(aString.begin(), aString.end(), aString.begin(), toupper);
if (aString == checkSuspect)
{
cout << aString << " is a suspect." << endl;
found = true;
}
}
if (!found)
{
cout << checkSuspect << " is not a suspect." << endl;
}
}
else if (command == "PRINT")
{
cout << "Current Suspects are:" << endl;
for (int k = 0; k < suspectIndex; k++)
{
if (suspectsArray[k] != "")
{
cout << suspectsArray[k] << endl;
}
}
}
else if (command == "ADD" || command == "QUIT" || command == "INQUIRY")
{
return command;
}
}
} // end INQUIRY
答案 0 :(得分：1)
我的猜测是你的程序没有在输入流中找到“/”，因此从不设置finishRecord = true;。您可能应该在内循环和外循环中检查eof。
答案 1 :(得分：0)
使用Visual Studio而不是Mac编译时这种方法有效的原因是你运气不好。你有一个错误使它看起来就像在Windows上工作一样，但Mac更幸运并且失败了。
从readFile函数开始，因为如果无法正确读取文件，则无法测试程序的其余部分。垃圾在==垃圾输出。
if (!myfile.peek() == myfile.eof())
以int两个块的形式分解，然后比较其结果。
!myfile.peek()
返回所有错误的读取字符或EOF。那不是吗。除非从文件中读取NULL，否则会导致false。
myfile.eof()
如果查看文件的末尾，则总是返回true，否则返回false。
如果不进入if的正文，那么空文件大小写将false与true进行比较。不知道你如何在这里获得无限循环。
至于
while (!myfile.eof())
阅读Why is iostream::eof inside a loop condition considered wrong?
getline(myfile, name)返回对输入流的引用，输入流有一个groovy operator bool()，如果流是可读的，则返回true，所以
while (getline(myfile, name))
实际上就是你所需要的。如果因任何原因无法读取文件，包括EOF，繁荣！该计划已离开这里。
这意味着所有输入都可以简化为：
while (getline(myfile, name))
{ // loop until read fails
string aString;
while (getline(myfile, aString) && aString != "/")
{ // loop until read fails or find end of record
list1.insert(index, aString);
index += 1;
}
KeyedItem an_item(name, list1, true);
loadTree.searchTreeInsert(an_item);
//reset variables used for each record
index = 1;
list1.removeAll();
}
尽管有一个强有力的案例可以单独捕获aString != "/"，因此程序可以在当前记录结束之前处理文件结束（或以其他方式变得不可读）。上面的代码只是包装起来，并称它为一天好像没有出错。
while (getline(myfile, name))
{ // loop until read fails
string aString;
while (getline(myfile, aString) && aString != "/")
{ // loop until read fails or find end of record
list1.insert(index, aString);
index += 1;
}
if (!myfile)
{
// handle error
}
KeyedItem an_item(name, list1, true);
loadTree.searchTreeInsert(an_item);
//reset variables used for each record
index = 1;
list1.removeAll();
}
填补这一空白。
此外，利用Visual Studio的调试器逐步执行代码并查看出错的地方。这将为您节省大量时间。
我们没有节点或树的代码，所以我们无法提供更多帮助。但是一旦你知道你有数据并且知道它是正确的（再次使用调试器来查看你的节点和树以确保一切正常），你要么已经完成或者处于有利位置要求新的，多更具体的问题。