问题描述
对于上下文，我创建了一个基本的“电子邮件模拟器”，您可以使用该模拟器向自己发送电子邮件，阅读电子邮件以及删除电子邮件。我必须在此方法中使用堆栈链接列表样式的方法，这就是标准。
到目前为止，我已经发现问题出在displayInBox函数上，但是到底出了什么问题我不确定，因为据我所知，它确实可行。但是我不确定，因为它不提供错误代码或触发本地Windows调试器，它只是冻结。
要触发与我相同的错误，只需撰写2封电子邮件，然后检查收件箱。您之间是否选中收件箱都没有关系。 我曾经能够做到，但是现在我做不到。 我正在使用VS2019作为参考。
我不是很有经验，所以它可能很肿，所以它很大。但是我尽了最大的努力使它的长度从600多行缩短到280行左右，但是您仍然可以使错误发生。这是指向完整程序的pastebin链接，以防万一 https://pastebin.com/Hp3uP0B9
#include <iostream>
#include <string>
#include <stdlib.h>
#include <windows.h>
using namespace std;
struct Email //just a basic struct
{
string data;
int index{}; //every new email will have a different index,used to traverse and pinpoint the correct email.
Email* prev{},* next{}; //just prevIoUs and next nodes
};
Email* myTemplate() //used to initialise a struct (alternative of constructor)
{
Email* temp = new Email;
temp->data = "\0";
temp->index = 0;
temp->next = NULL;
temp->prev = NULL;
return temp;
};
struct UI //another basic struct,but using constructors
{
UI* prev,* next; //prevIoUs and next nodes
string text[2]; //stores the selected text and unselected text
bool selected; //bool to kNow when to trigger selected text
int menuFunc; //used to determine which function to call,can also be used to represent Email's index when passing in values
UI()
{
prev = NULL;
next = NULL;
text[0] = "\0";
text[1] = "\0";
selected = false;
menuFunc = -1;
}
UI(UI* myPrev,UI* myNext,int myMFunc,string myText)
{
prev = myPrev;
next = myNext;
menuFunc = myMFunc;
text[0] = myText;
text[1] = "<<" + text[0] + ">>";
selected = false;
}
};
int mainMenu()
{
int temp;
cout << "type 1 to compose email,type 2 to display inBox,type 99 to quit\n: ";
cin >> temp;
if (temp == 1||temp == 2||temp == 99)
{
return temp;
}
else
{
return mainMenu();
}
}
int getKeyInt() //just a function to get relevant key codes
{
if (GetAsyncKeyState(VK_UP))
{
return VK_UP;
}
else if (GetAsyncKeyState(VK_DOWN))
{
return VK_DOWN;
}
else if (GetAsyncKeyState(VK_RETURN))
{
return VK_RETURN;
}
else if (GetAsyncKeyState(VK_ESCAPE))
{
return VK_ESCAPE;
}
else
{
return -1;
}
}
void displayInBox(UI* myNavi,UI* myHead,UI* myTail,Email*& eNavi,Email*& eHead,Email*& eTail) //displays the inBox of the mail
{
bool modified = false;
bool tempRunFlag = true;
int tempKeyPress;
UI* refreshCache = myHead; // to log the navigator's location upon reprinting the screen,points to head before the loop begins
myNavi = myHead; //points the navigator to the newest node in the list
eNavi = eTail; //email navigator switches address to the newest node in the email linked list
if (eNavi->data != "\0") //to check if newest mail has values,just in case
{
myNavi->menuFunc = eNavi->index; //assigns the email index to the "menuFunc" to be passed when calling deleteMail() and displayMail()
myNavi->text[0] = eNavi->data; //sets the UI text of navigator
myNavi->text[1] = "<<" + myNavi->text[0] + ">>";
myHead = myNavi;//setting myHead to point to navigator's current address
myHead->selected = true; //this will trigger the selected text's output later
refreshCache = myHead;// assigns refreshCache to myHead
myTail = myHead; //if it's only 1 mail in the list,then this will prevent UI from traversing into NULL,if not,below will change the values
if (eNavi->prev != NULL)//if email navigator has a earlier mail to point to,false if there's only 1 element in the list,which is already done above
{
while (eNavi != NULL)//if email navigator is not pointing to the earliest mail,or if theres only 1 element
{
if (eNavi != eHead) //double checking if email navigator hasn't reached the earliest mail yet,if it is,then no need to go even earlier
{
eNavi = eNavi->prev; //email navigator approaches eHead by 1 node
}
myNavi->next = new UI(myNavi,NULL,eNavi->index,eNavi->data); //creates a new node to point to
myNavi = myNavi->next; // navigator switch to the next address that it created
myTail = myNavi; //assigns tail to newly created UI navigator node
}
}
}
else //if newest mail has no values,or no mail
{
myHead = new UI(NULL,"nothing to see here");
myHead->selected = true;
refreshCache = myHead;
myTail = myHead;
}
while (tempRunFlag)
{
system("CLS");
cout <<
"\nNow browsing inBox..." << endl <<
"____________________________________________________________________________________________________" << endl <<
"MAIL DATA"<< endl;
myNavi = myHead; //UI navigator will be reassigned to point to first UI
while (myNavi != NULL)
{
cout << myNavi->text[(int)myNavi->selected] << endl;
myNavi = myNavi->next;
}
myNavi = refreshCache;//similar implementation in the prompt() function;
if (myNavi != NULL)
{
cout << "\nMenu Function code: " << myNavi->menuFunc << endl;//used for debugging,displays the menuFunc
}
cout <<
"\n\nReached end of inBox" << endl <<
"____________________________________________________________________________________________________" << endl <<
"[Use ARROW KEYS UP & DOWN to navigate,ESC to return to Main Menu]" << endl;
system("pause");
tempKeyPress = getKeyInt();
switch (tempKeyPress)
{
case VK_UP:
if (myNavi != myHead)
{
myNavi->selected = false;
myNavi = myNavi->prev;
myNavi->selected = true;
refreshCache = myNavi;
}
break;
case VK_DOWN:
if (myNavi != myTail)
{
myNavi->selected = false;
myNavi = myNavi->next;
myNavi->selected = true;
refreshCache = myNavi;
}
break;
case VK_ESCAPE:
tempRunFlag = false;
break;
default:
break;
}
}
return;
}
void composeEmail(Email*& eHead,Email*& eTail) //prompting the user to get data
{
Email* draft = new Email;
system("CLS");
if (eHead->data != "\0") ///used to get rid of a \n character in the buffer for no reason,I don't kNow why it's there,but whats weird is that it only happens once the email linked list already has 1 element inside of it
{
cin.ignore();
}
do
{
cout << "\nPlease type in data (16 character limit)" << endl; //just for no reason
getline(cin,draft->data);
} while (draft->data.length() > 16 || draft->data.length() <= 0);
while (draft->data.length() < 16)
{
draft->data += " ";
}
cout << "\n\nEmail is sent! Please check inBox." << endl;
draft->next = NULL;
if (eHead->data == "\0") //if current head node is empty
{
draft->prev = NULL;
draft->index = eTail->index + 1;
eHead = draft;
eTail = eHead;
}
else //if head node already has a value
{
draft->prev = eTail;
draft->index = eTail->index + 1;
eTail->next = draft;
eTail = draft;
}
system("pause");
}
bool mainMenuExecute(int executionCode,UI* uiNaviIB,UI* uiHeadIB,UI* uiTailIB,Email*& eTail)
{
if (executionCode == 1)
{
composeEmail(eHead,eTail);
return true;
}
else if (executionCode == 2)
{
displayInBox(uiNaviIB,uiHeadIB,uiTailIB,eNavi,eHead,eTail);
return true;
}
else if (executionCode == 99)
{
return false;
}
}
int main()
{
//InBox UI
UI* uiHeadIB = new UI(NULL,"nothing to see here"),* uiTailIB = uiHeadIB,* uiNaviIB = uiHeadIB;
uiNaviIB->selected = true;
//Actual mail stuff
Email* mHead = myTemplate(),* mTail = mHead;
Email* mNavi = mHead;
bool simulate = true;
while (simulate)
{
system("CLS");
simulate = mainMenuExecute(mainMenu(),uiNaviIB,mNavi,mHead,mTail);
}
}
希望有人可以在我学到更多东西时提出建设性的批评，干杯。
解决方法
我解决了这个问题，但是还有另一个问题，但是那是另一种情况，至于我是如何解决的，我在if（eNavi！= eHead）之后放置了else {break;}，因为它引起了while循环如果不中断，可以无限循环。