C++ 为什么打印的值都是垃圾？我们如何解决这个问题？

我只是想知道。 你看，我们为一个叫做魔术数字游戏（3x3）的游戏制作了一个程序。但在我们的程序中，用户将输入所有九个数字，并且程序将检查输入的数字在水平、垂直和对角添加时是否全部合计为15

我们使用simple

cin/cout

方法得到了正确的算法，具有正确的输出，但我们需要使用类

当我们这样做的时候，输入是正确的，但是当数字和总和被打印出来时，程序打印的是垃圾存储器，而不是用户输入的内容。这是我们目前掌握的代码

#include <iostream>
#include <iomanip>
#include <windows.h>
#include <stdlib.h>

using namespace std;
class magicNumber {
public:
    void inputNum(int, int, int, int, int, int, int, int, int);
    void check();
    void displayResults();
    void decision();
    magicNumber();

private:
    int a, b, c, d, e, f, g, h, i;
    int row1, row2, row3, col1, col2, col3, dia1, dia2;
};
magicNumber::magicNumber() {
    int a, b, c, d, e, f, g, h, i = 0;
    int row1, row2, row3, col1, col2, col3, dia1, dia2 = 0;
}

void magicNumber::inputNum(int, int, int, int, int, int, int, int, int) {
    cout << "Enter three numbers for the first row (seperate by space): ";
    cin >> a >> b >> c;
    cout << "Enter three numbers for the next row (seperate by space):  ";
    cin >> d >> e >> f;
    cout << "Enter three numbers for the last row (seperate by space):  ";
    cin >> g >> h >> i;
    cout << endl;
}
void magicNumber::check() {
    int check = 0;
    int a, b, c, d, e, f, g, h, i;
    int row1, row2, row3, col1, col2, col3, dia1, dia2;
    row1 = a + b + c;
    if (row1 != 15)
        (check++);

    row2 = d + e + f;
    if (row2 != 15)
        (check++);

    row3 = g + h + i;
    if (row3 != 15)
        (check++);

    col1 = a + d + g;
    if (col1 != 15)
        (check++);

    col2 = b + e + h;
    if (col2 != 15)
        (check++);

    col3 = c + f + i;
    if (col3 != 15)
        (check++);

    dia1 = c + e + g;
    if (dia1 != 15)
        (check++);

    dia2 = a + e + i;
    if (dia2 != 15)
        (check++);
}

void magicNumber::displayResults() {
    int a, b, c, d, e, f, g, h, i;
    int row1, row2, row3, col1, col2, col3, dia1, dia2;

    cout << "                        = " << dia1 << "\n";
    cout << "+++++++++++++++++++++++++\n";
    cout << "+       +       +       +\n";
    cout << "+   " << a << "   +   " << b << "   +   " << c << "   + = " << row1
         << "\n";
    cout << "+       +       +       +\n";
    cout << "+++++++++++++++++++++++++\n";
    cout << "+       +       +       +\n";
    cout << "+   " << d << "   +   " << e << "   +   " << f << "   + = " << row2
         << "\n";
    cout << "+       +       +       +\n";
    cout << "+++++++++++++++++++++++++\n";
    cout << "+       +       +       +\n";
    cout << "+   " << g << "   +   " << h << "   +   " << i << "   + = " << row3
         << "\n";
    cout << "+       +       +       +\n";
    cout << "+++++++++++++++++++++++++\n";
    cout << "  = " << col1 << "    = " << col2 << "    = " << col3 << "    = "
         << dia2 << "\n";
    cout << endl;
    cout << endl;
}
void magicNumber::decision() {

    int check = 0;
    char ans;
    if (check != 0) {
        cout << "YOU FAILED. TRY AGAIN? [Y/N]: ";
        cin >> ans;

        switch (ans) {
            case 'Y':
            case 'y':
                int main();

            case 'N':
            case 'n':
                cout << "\nTHANK YOU, PLAY AGAIN!!";
                break;
        }

    }

    else if (check == 0)
        cout << "YOU WON!! CONGRATULATIONS!\n\n";
    cout << endl;
}

int main() {
    system("CLS");

    int check;
    char ans;

    magicNumber numbers;

    cout << "Welcome to Magic Square Number game!\n"
         << "Please fill out the 3 x 3 grid with numbers \n"
         << "1 to 9 without repeating any digits. The sum\n"
         << " should be 15 when the numbers are added horizontally, \n"
         << "vertically, or diagonally.\n\n";

    numbers.inputNum(0, 0, 0, 0, 0, 0, 0, 0, 0);
    numbers.check();
    numbers.displayResults();
    numbers.decision();

    system("PAUSE");
}

#包括
#包括
#包括
#包括
使用名称空间std；
类magicNumber{
公众：
void inputNum（int，int，int，int，int，int，int，int，int，int）；
无效检查（）；
void displayResults（）；
无效判决（）；
magicNumber（）；
私人：
INTA、b、c、d、e、f、g、h、i；
int row1，row2，row3，col1，col2，col3，dia1，dia2；
};
magicNumber:：magicNumber（）{
int a，b，c，d，e，f，g，h，i=0；
int row1，row2，row3，col1，col2，col3，dia1，dia2=0；
}
void magicNumber:：inputNum（int，int，int，int，int，int，int，int，int，int，int）{
cout>a>>b>>c；
cout>d>>e>>f；
cout>g>>h>>i；
cout您在每个例程中都在本地重新声明整数变量。这不仅隐藏了成员变量，而且将它们初始化为它们之前堆栈上的任何变量。正确的解决方法是删除它们，然后使用成员变量

在实践中，在类成员变量上添加某种前缀/后缀有助于将其与局部变量区分开来。例如：

class Foo
{
    int fVariable;
    int variable_;
    int variable_m;
    int m_variable;
};

通过这些装饰，更容易识别变量的范围和所有权：

void Foo::ClassRoutine()
{
    int variable;

    variable = 0; // local variable
    variable_m = 0; // class member variable
}

您声明了以下成员变量：

class magicNumber
{
  //... 
  int a,b,c,d,e,f,g,h,i;
  int row1, row2, row3, col1, col2, col3, dia1, dia2;

然后，在
检查（）

在
displayResults（）
中：

您使用相同的名称声明局部变量。共享的
a
、
b
等都不会被任何一种方法查看或触及

删除本地声明，以便使用成员变量

void magicNumber::displayResults()
{   
  cout<<"                        = "<<dia1<<"\n";
  // etc.

void magicNumber:：displayResults（）
{   
cout对于直接的问题，只需删除与成员变量同名的局部变量即可


既然你被告知要使用一个类，我想我最好对此进行评论

您已经使用类机制实现了一个过程逻辑：这样做，然后这样做，依此类推

但是想一想，如果控制台i/o被GUI取代，那么这个类会有多大用处？就这一点而言，它现在有多大用处？答案是，它不是很有用，只是一个复杂问题

相反，将类的对象视为自动化，具有一些内部状态（私有数据成员）和一些可见按钮（公共成员函数）。按下任何按钮都会使自动化执行某些操作，可能会更改其内部状态。在这种特殊情况下，有用的内部状态是9个值和一个有用的“按钮”可以是通过
bool
函数结果报告这些数字是否构成幻方的成员函数

其他功能可能包括设置数字


最后，您可能需要考虑<代码> STD:：数组< /COD>用于保存数字，并循环进行检查。
 < P>代码中的一些问题：


您在该类的方法中声明的变量与类
magicNumber
的成员变量同名。我假设您只想使用成员变量，而不想隐藏（当您在内部作用域中声明一个与外部作用域同名的变量时，后者是隐藏的，前者在内部作用域中可见）
您在
decision
方法中遇到了case语句。当您调用
main（）
时，您总是在稍后执行
cout a>>b>>c；
cout>d>>e>>f；
cout>g>>h>>i；
你不能声明与成员变量同名的局部变量。不要。谢谢你的回答。我们将尝试应用你告诉我的所有内容来改进我们的程序。谢谢！我们终于修复了错误，谢谢大家。也谢谢你的提示，先生。我们非常感谢你的帮助。
void magicNumber::displayResults()
{   
  int a,b,c,d,e,f,g,h,i;

void magicNumber::displayResults()
{   
  cout<<"                        = "<<dia1<<"\n";
  // etc.

#include <iostream>
#include <iomanip>
#include <windows.h>
#include <stdlib.h>

void gameplay();

using namespace std;
class magicNumber {
public:
    void inputNum(int, int, int, int, int, int, int, int, int);
    void check();
    void displayResults();
    void decision();
    magicNumber();

private:
    int a, b, c, d, e, f, g, h, i;
    int row1, row2, row3, col1, col2, col3, dia1, dia2;
};
magicNumber::magicNumber() {
    a = b = c = d = e = f = g = h = i = 0;
    row1 = row2 = row3 = col1 = col2 = col3 = dia1 = dia2 = 0;
}

void magicNumber::inputNum(int, int, int, int, int, int, int, int, int) {
    cout << "Enter three numbers for the first row (seperate by space): ";
    cin >> a >> b >> c;
    cout << "Enter three numbers for the next row (seperate by space):  ";
    cin >> d >> e >> f;
    cout << "Enter three numbers for the last row (seperate by space):  ";
    cin >> g >> h >> i;
    cout << endl;
}
void magicNumber::check() {
    int check = 0;
    row1 = a + b + c;
    if (row1 != 15)
        (check++);

    row2 = d + e + f;
    if (row2 != 15)
        (check++);

    row3 = g + h + i;
    if (row3 != 15)
        (check++);

    col1 = a + d + g;
    if (col1 != 15)
        (check++);

    col2 = b + e + h;
    if (col2 != 15)
        (check++);

    col3 = c + f + i;
    if (col3 != 15)
        (check++);

    dia1 = c + e + g;
    if (dia1 != 15)
        (check++);

    dia2 = a + e + i;
    if (dia2 != 15)
        (check++);
}

void magicNumber::displayResults() {
    cout << "                        = " << dia1 << "\n";
    cout << "+++++++++++++++++++++++++\n";
    cout << "+       +       +       +\n";
    cout << "+   " << a << "   +   " << b << "   +   " << c << "   + = " << row1
         << "\n";
    cout << "+       +       +       +\n";
    cout << "+++++++++++++++++++++++++\n";
    cout << "+       +       +       +\n";
    cout << "+   " << d << "   +   " << e << "   +   " << f << "   + = " << row2
         << "\n";
    cout << "+       +       +       +\n";
    cout << "+++++++++++++++++++++++++\n";
    cout << "+       +       +       +\n";
    cout << "+   " << g << "   +   " << h << "   +   " << i << "   + = " << row3
         << "\n";
    cout << "+       +       +       +\n";
    cout << "+++++++++++++++++++++++++\n";
    cout << "  = " << col1 << "    = " << col2 << "    = " << col3 << "    = "
         << dia2 << "\n";
    cout << endl;
    cout << endl;
}
void magicNumber::decision() {

    int check = 0;
    char ans;
    if (check != 0) {
        cout << "YOU FAILED. TRY AGAIN? [Y/N]: ";
        cin >> ans;

        switch (ans) {
            case 'Y':
            case 'y':
                gameplay();
                break;

            case 'N':
            case 'n':
                cout << "\nTHANK YOU, PLAY AGAIN!!";
                break;
        }

    }

    else if (check == 0)
        cout << "YOU WON!! CONGRATULATIONS!\n\n";
    cout << endl;
}

void gameplay() {
    magicNumber numbers;

    cout << "Welcome to Magic Square Number game!\n"
         << "Please fill out the 3 x 3 grid with numbers \n"
         << "1 to 9 without repeating any digits. The sum\n"
         << " should be 15 when the numbers are added horizontally, \n"
         << "vertically, or diagonally.\n\n";

    numbers.inputNum(0, 0, 0, 0, 0, 0, 0, 0, 0);
    numbers.check();
    numbers.displayResults();
    numbers.decision();
}

int main() {
    system("CLS");

    gameplay();

    system("PAUSE");
}