Question

我正在进行一项任务，而且我已经在将一个数据组的新成员添加到链接列表时遇到了一些障碍。我用Google搜索并全神贯注但我无法找到问题的解决方案。问题是当我在Openbutton_Click中打开文件时，我最初声明的6个变量（客户和5个节点类型变量）最初被修改。但我以后无法在addconf_Click中修改变量。通常我不会发帖求助，但我已经没时间了，也无法解决这个问题。我在格式化方面遇到了很多麻烦，请耐心等待。

这是myform.h附带的.cpp文件

#include "MyForm.h"

using namespace System; 
using namespace System::Windows::Forms; 
using namespace std;

int customers = 0;
node *current;
node *first;
node *last;
node *temp;
node *previous;


[STAThread] 
void Main(array<String^>^ args) { 
Application::EnableVisualStyles(); 
Application::SetCompatibleTextRenderingDefault(false); 

Project1::MyForm form;

Application::Run(%form); 
}

这完全在myform.h中

#pragma once
#include <fstream>
#include <string>
#include <iostream>
#include <sstream>
#include <msclr\marshal_cppstd.h>
#include "header.h"

using namespace std;

struct node{
account customer;
node *next;

};

extern int customers;
extern node *current;
extern node *first;
extern node *last;
extern node *temp;
extern node *previous;

private: System::Void Openbutton_Click(System::Object^  sender, System::EventArgs^  e) {
ifstream fin;

openFileDialog1->ShowDialog();

String^ filenname = System::IO::Path::GetFileName(openFileDialog1->FileName);
std::string filename = msclr::interop::marshal_as<std::string>(filenname);

fin.open(filename);


if (fin){
    this->label2->Text = "File Opened";
}
else
    this->label2->Text = "Failed to Open File";

String^ menu;
String^ temp;
string input;
string name;
string numstr;
string pinstr;
string balstr;
int num;
int pin;
float bal;

first = new node;

getline(fin, input);

numstr = input.substr(0, 3);

stringstream convert3(numstr);
convert3 >> num;


name = input.substr(8, 16);

name.erase(name.find_last_not_of(" \n\r\t") + 1);

pinstr = input.substr(24, 4);


balstr = input.substr(30, 7);



stringstream convert(pinstr);
convert >> pin;

stringstream convert2(balstr);
convert2 >> bal;

first->customer.setNum(num);
first->customer.setName(name);
first->customer.setPin(pin);
first->customer.setBal(bal);
first->next = 0;

numstr.clear();
name.clear();
pinstr.clear();
balstr.clear();

current = first;

customers++;

while (fin){
    customers++;
    previous = current;
    current->next = new node;
    current = current->next;

        getline(fin, input);

        numstr = input.substr(0, 3);

        name = input.substr(8, 16);

        name.erase(name.find_last_not_of(" \n\r\t") + 1);

        pinstr = input.substr(24, 4);

        balstr = input.substr(30, 7);

        stringstream convert3(numstr);
        convert3 >> num;

        stringstream convert(pinstr);
        convert >> pin;

        stringstream convert2(balstr);
        convert2 >> bal;


        current->customer.setNum(num);
        current->customer.setName(name);
        current->customer.setPin(pin);
        current->customer.setBal(bal);

    }
    last = previous;
    last->next = 0;
    customers--;
    cout << "All accounts loaded, system ready." << endl;
    // Print and fill the textbox
    current = first;

    menu = "Account List:" + customers + "\r\n " + "Num | Account Holder | Pin | Balance\r\n";


    for (int c = 0; c < customers; c++){
        menu += current->customer.getNum();
        menu += " | ";
        temp = gcnew String(current->customer.getName().c_str());
        menu += temp;
        menu += " | ";
        menu += current->customer.getPin();
        menu += " | $";
        menu += current->customer.getBal();
        menu += "\r\n";

        if (current->next != 0){
            current = current->next;
        }
        else
            c = customers;
    }


textBox1->Text = gcnew String(menu);
launch->Visible = true;
addCust->Visible = true;
remCust->Visible = true;
refList->Visible = true;
}

private: System::Void addconf_Click(System::Object^  sender, System::EventArgs^  e) {
int num = -1;
string name = "";
int pin = -1;
float bal = -1;
bool match = false;

string numstr = msclr::interop::marshal_as<std::string>(addnumbox->Text);
num = stoi(numstr);
name = msclr::interop::marshal_as<std::string>(addnamebox->Text);


name.erase(name.find_last_not_of(" \n\r\t") + 1);
string pinstr = msclr::interop::marshal_as<std::string>(addpinbox->Text);
pin = atoi(pinstr.c_str());

string balstr = msclr::interop::marshal_as<std::string>(addbalbox->Text);
bal = stof(balstr);

if (num != -1 && pin != -1 && name != "" && bal != -1){

    current = new node;
    last->next = current;
    current->customer.setNum(num);
    current->customer.setName(name);
    current->customer.setPin(pin);
    current->customer.setBal(bal);
    current->next = 0;


    last = current;
    customers = customers + 1;
    num = -1;
    pin = -1;
    name = "";
    bal = -1;


    }


}

header.h就在这里

#include <string>
#include <iostream>

using namespace std;


class account{
private:
int accNum;
int accPin;
string accName;
float accBal;

public:
void setNum(int num);
void setPin(int pin);
void setName(string name);
void setBal(float bal);
void deposit(float money);
void withdraw(float money);

int getNum();
int getPin();
string getName();
float getBal();
};

void account::setNum(int num){
accNum = num;
}

void account::setPin(int pin){
accPin = pin;
}

void account::setName(string name){
accName = name;
}

void account::setBal(float bal){
accBal = bal;
}

int account::getNum(){
return accNum;
}

int account::getPin(){
return accPin;
}

string account::getName(){
return accName;
}

float account::getBal(){
return accBal;
}

void account::deposit(float money){
accBal = accBal + money;
}

void account::withdraw(float money){
accBal = accBal - money;
}

Answer 1

您将customers声明为头文件中的int。请记住，头文件是文法粘贴到它所包含的文件中。因此，您将拥有该变量的许多实例。

正确的方法是在cpp文件中定义它，并在头文件中使用extern int customers使其全局化。

同样的问题适用于您的nodes - 变量。您必须在cpp文件中定义它们，以便它们只存在于一个位置。

但是，使用像这样的全局可变变量几乎不是一个好主意。

Answer 2

原来我错过了一行代码，正确打印出列表的当前状态。现在感觉像个完全白痴。感谢那些帮助过你的人。

C ++：无法修改全局变量

2 个答案: