Question

我有一个switch语句菜单，具有以下要求：

“ GetNewMatrix”作为枚举选项，其值为0到9之间的数字。
用户输入的内容必须全部一行。
必须使用枚举。

我需要用户能够输入“ GetNewMatrix 5”之类的内容，并让switch语句查看GetNewMatrix来启动该情况，并将5传递给该情况以初始化matrix [5] .MatrixType（）

我对如何准确实现这一点完全迷失了。我目前有以下（相当粗略的）代码，尽管这不能帮助我从用户输入中提取用户整数，因为如上所述需要在所有一行中完成。

矩阵是MatrixType类的大小为[10]的数组，其中包含int值[MAX_ROWS] [MAX_COLS]，int numRows和int numCols
input是一个字符串，用于获取用户输入并将其与枚举案例进行比较，以确定继续处理哪种案例
name是介于0到9之间的整数，用于在[10]数组中标记矩阵。
r是一个整数，用于保存用户指定的行数

c是用于保存用户指定的列数的整数

enum Choice {Start, GetNewMatrix, AddMatrices, SubMatrices, MultiplyMatrices, PrintMatrix, Quit};
Choice ch = Start;

while(ch != Quit)
{
    cout << "=======================================================" << endl;
    cout << "GetNewMatrix # (Create a new Matrix)" << endl;
    cout << "AddMatrices # # # (Adds two matrices together)" << endl;
    cout << "SubMatrices # # # (Subtracts a second matrix from the first)" << endl;
    cout << "MultiplyMatrices # # # (Multiplies two matrices together)" << endl;
    cout << "PrintMatrix # (Print out a matrix)" << endl;
    cout << "Quit (Quit the program)" << endl;
    cout << "=======================================================" << endl << endl;
    cout << "Please enter your choice here: ";

    cin >> input; //Unable to assign ch to a string
    if (input == "GetNewMatrix")
    { 
        ch = GetNewMatrix;
    } 
    else
    if (input == "Quit") 
    {
        ch = Quit;
    } 
    else 
    {
        cout << "Unknown entry. Please use exact capitalization." << endl;
    }

    switch(ch)
    {
        case GetNewMatrix: //Placeholder until integer extraction is figured out
            cout << "Please enter a value (between 0 and 9) to name the matrix: ";
            cin >> name;
            matrix[name].MatrixType();
            cout << "Matrix " << name << " created." << endl;

            cout << "Please enter values (between 1 and 10) for row and coloum size: ";
            cin >> r >> c;
            matrix[name].SetSize(r - 1,c - 1);
            cout << "Matrix size set to " << r << " x " << c << endl; 


            break;

Answer 1

您可能现在看到的枚举背后的工作就像一个数组索引，它从0开始，依此类推，因此使用char可以使您的char ch;像这样int ch的int变量；然后您可以将int中的输入作为选择，然后根据要运行的输入将其作为0到9进行切换。

Answer 2

使用User4581301的信息（感谢您的其他帖子以及添加的信息），我可以使用以下内容：

int main()
{
string input;
int count = 0;
int i;
int j;
int item;
int num1;
int num2;
int num3;
string case_value;
int r; //used for row size
int c; //used for coloumn size
MatrixType matrix[10];

enum Choice {Start, GetNewMatrix, AddMatrices, SubMatrices, MultiplyMatrices, PrintMatrix, Quit};
Choice ch = Start;

while(ch != Quit)
{
    cout << "=======================================================" << endl;
    cout << "GetNewMatrix # (Create a new Matrix)" << endl;
    cout << "AddMatrices # # # (Adds two matrices together)" << endl;
    cout << "SubMatrices # # # (Subtracts a second matrix from the first)" << endl;
    cout << "MultiplyMatrices # # # (Multiplies two matrices together)" << endl;
    cout << "PrintMatrix # (Print out a matrix)" << endl;
    cout << "Quit (Quit the program)" << endl;
    cout << "=======================================================" << endl << endl;
    cout << "Please enter your choice here: ";

    if(count > 0)
    {
        cin.ignore();
    }
    getline(cin, input);
    istringstream copy;
    copy.str (input);

    count++;

    copy >> case_value;
    copy >> num1; //value used in the first # of EACH case if it has one
    copy >> num2; //value used in the second # of EACH case if it has one
    copy >> num3; //value used in the third # of EACH case if it has one

    if (case_value == "GetNewMatrix")
    { 
        ch = GetNewMatrix;
    } 
    else
    if (case_value == "PrintMatrix")
    {
        ch = PrintMatrix;
    }
    else
    if (case_value == "Quit") 
    {
        ch = Quit;
    } 
    else 
    {
        cout << "Unknown entry. Please use exact capitalization." << endl;
    }

    switch(ch)
    {
        case GetNewMatrix: 
        {
            cout << "Matrix " << num1 << " obtained." << endl;

            cout << "Please enter values (between 1 and 10) for row and coloum amount: ";
            cin >> r >> c;
            matrix[num1].SetSize(r,c);
            cout << "Matrix size set to " << r << " x " << c << " reading up->down then left->right." << endl; 

            i = 0;
            while (i < c)
            {
                cout << "Please enter the " << r << " value(s) for coloumn " << i + 1 << " seperated by spaces: ";
                cin.ignore();
                getline(cin, input);
                istringstream copy;
                copy.str (input); 

                for (j = 0; j < r; j++)
                {
                    int temp;
                    copy >> temp;
                    matrix[num1].StoreItem(temp, i, j);
                }
                i++;
            }
            break;
        }

从用户输入中提取整数的经过放大的switch语句

2 个答案: