Question

我只是想知道。你看，我们为一款名为Magic number game（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，程序将检查输入的数字在水平，垂直和对角线上添加时是否总计为15。

我们使用简单的cin/cout方法得到了正确的算法，输出正确，但我们需要使用类。

当我们这样做时，输入是正确的，但是当打印数字和总和时，程序会打印垃圾记忆，而不是输入用户输入的内容。以下是我们目前的代码。

#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");
}

Answer 1

您将在每个例程中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的堆栈中的任何变量。正确的解决方法是删除它们，然后使用成员变量。

在实践中，在类成员变量上放置某种前缀/后缀以将它们与局部变量区分开是有帮助的。一些例子：

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

通过这些装饰，可以更容易地辨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
}

Answer 2

您声明了这些成员变量：

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

然后，在check()：

void magicNumber::check()
{
  int check = 0;
  int a,b,c,d,e,f,g,h,i;

和displayResults()：

void magicNumber::displayResults()
{   
  int a,b,c,d,e,f,g,h,i;

您声明具有相同名称的局部变量。任何方法都不会查看或触及共享的a，b等。

删除局部声明，以便改为使用成员变量。

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

Answer 3

对于直接问题，只需删除与成员变量相同名称的局部变量。

既然你被告知要上课，我想我最好对此发表评论。

您已使用类机制实现过程逻辑：执行此操作，然后执行此操作，依此类推。

但是想想，如果控制台i / o被GUI取代，那么这个类有多大用处呢？就此而言，它现在有用吗？答案，它不是很有用，它只是一个复杂的问题。

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做一些事情，可能会改变其内部状态。在这种特殊情况下，有用的内部状态是9个值，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std::array来保存数字，并循环来进行检查。

Answer 4

代码中的一些问题：

您声明的变量与该类的方法中类magicNumber的成员变量具有相同的名称。我假设您只想使用成员变量而不是隐藏（当您在内部作用域中声明一个与外部作用域相同的名称时，后者隐藏，前者在内部作用域中可见）。
您正在使用decision方法中的case语句。当您致电main()时，您随后会执行cout << "\nTHANK YOU, PLAY AGAIN!!";。
调用main方法确实是个坏主意。提取调用其他方法所需的功能。

固定代码（不知道它是否有效，check方法对于我能看到的内容是不完整的，但是编译好并修复所描述的问题）：

#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");
}

其他一些建议：

如果用户想要，您需要在decision方法中使用循环来重复游戏。

为什么印刷的价值都是垃圾？我们该如何解决这个问题？

4 个答案: