如何从main（C+；+；）访问函数中的值 #包括 #包括 使用名称空间std； //常数： const int MIN_HEIGHT=3； const int MIN_WIDTH=3； const int MAX_HEIGHT=20； const int MAX_WIDTH=60； 常量字符H='H'； 常量字符W='W'； 常量字符B='B'； 常量字符F='F'； const char Q='Q'； //原型： void draw矩形（int行、int列、字符边框、字符填充）； 无效显示选项（）； char getChoice（char h、char w、char b、char f、char q）； int main（） { 字符边框，填充，选择； 如果你是C++中定义函数的新手，我当然会建议你尝试一些更小的程序。

您定义为函数

getChoice（char，char，char，char，char，char）

的返回类型的类型是

char

，但函数中的所有返回值（neworder除外）的类型都是

int

，这是不合适的

事实上，从函数“getChoice”的名称判断，该函数应该只返回用户的“choice”，而不是进一步，进一步的指令应该在其他地方执行

当用户输入“q”时，getChoice中的return 0语句不会导致主函数退出，而只会导致getChoice函数返回int值0

在判断用户的选择时，我还考虑了一个比所有IF语句更好的切换情况语句。 在我根据您的程序编写的以下代码中，将在主函数内执行更多指令

#include <iostream>
#include <cassert>
using namespace std;

//constants:
const int MIN_HEIGHT = 3;
const int MIN_WIDTH = 3;
const int MAX_HEIGHT = 20;
const int MAX_WIDTH = 60;
const char H = 'h';
const char W = 'w';
const char B = 'b';
const char F = 'f';
const char Q = 'q';

//prototypes:
void drawRectangle(int row, int col, char border, char fill);
void displayChoices();
char getChoice(char h, char w, char b, char f, char q);

int main()
{

    char border, fill, choice; 

    cout << endl << "Welcome! \n"; 
    drawRectangle (10,10, '#','*');

    cout << endl << "Choose from the following: \n";
    displayChoices();
    getChoice(H, W, B, F, Q);
    //drawRectangle();//not sure how to get the changed value from getChoice
    //if height is changed, update height. If width is changed, update width of rect.
    //if border is changed, update rectangle border. If fill is changed, update rectangle fill

}

//draws rectangle
void drawRectangle(int row, int col, char border, char fill)
{
    for (int i = 0; i < row; i++) {
        for (int j = 0; j < col; j++) {
            if ((i == 0) || (i == (row - 1)) || (j == 0) || (j == (col - 1))) {
                cout << border;
            }
            else {
                cout << fill;
            }
        }
        cout << endl;
    }
}

//diplays users choices between height, width
//border and quit
void displayChoices()
{
    cout << "h) Change the height.\n";
    cout << "w) Change the width.\n";
    cout << "b) Change the border character.\n";
    cout << "f) Change the fill character.\n";
    cout << "q) Quit program.\n";   
}

//takes users choice and asks for the new value or character 
char getChoice(char h, char w, char b, char f, char q) {
    char choice, newBorder, newFill;
    int newHeight, newWidth, count = 0;

    cin >> choice;

    while ((choice != h && choice != w && choice != b && choice != f && choice != q)) {
        cout << "Not a valid choice. Choose again.\n";
        cin >> choice;
    }

        if (choice == q)
            return 0;

        else if (choice == h) {
            cout << "Enter new height between " << MIN_HEIGHT << " and " << MAX_HEIGHT << ": \n";
            cin >> newHeight;
            while ((newHeight < MIN_HEIGHT) || (newHeight > MAX_HEIGHT)) {

                cout << "That number is not in range. Try again.\n";
                cout << "Enter a number between " << MIN_HEIGHT
                    << " and " << MAX_HEIGHT << ": ";
                cin >> newHeight;

            } return newHeight;
        }
        else if (choice == w) {
            cout << "Enter new width  between " << MIN_WIDTH << " and " << MAX_WIDTH << ": \n";
            cin >> newWidth;
            while ((newWidth < MIN_WIDTH) || (newWidth > MAX_WIDTH)) {

                cout << "That number is not in range. Try again.\n";
                cout << "Enter a number between " << MIN_WIDTH
                    << " and " << MAX_WIDTH << ": ";
                cin >> newWidth;

            } return newWidth;
        }
        else if (choice == b) {
            cout << "Enter new border character: \n";
            cin >> newBorder;
            return newBorder;
        }
        else if (choice == f) {
            cout << "Enter new fill character: \n";
            cin >> newFill;
            return newFill;

        }

    }

#包括
#包括
使用名称空间std；
//常数：
const int MIN_HEIGHT=3；
const int MIN_WIDTH=3；
const int MAX_HEIGHT=20；
const int MAX_WIDTH=60；
常量字符H='H'；
常量字符W='W'；
常量字符B='B'；
常量字符F='F'；
const char Q='Q'；
//原型：
void draw矩形（int行、int列、字符边框、字符填充）；
无效显示选项（）；
char getChoice（char h、char w、char b、char f、char q）；
int main（）
{
字符边框='#'，填充='*'，选项；
int newHeight=0；
int newWidth=0；
字符顺序=（字符）0；
char newFill=（char）0；
内部高度=10，宽度=10；
cout
const char H='H'；
就像写
const int one_一百_十七=117；
（有点奇怪）听起来你可以从阅读一本书中获益。
#include <iostream>
#include <cassert>
using namespace std;

//constants:
const int MIN_HEIGHT = 3;
const int MIN_WIDTH = 3;
const int MAX_HEIGHT = 20;
const int MAX_WIDTH = 60;
const char H = 'h';
const char W = 'w';
const char B = 'b';
const char F = 'f';
const char Q = 'q';

//prototypes:
void drawRectangle(int row, int col, char border, char fill);
void displayChoices();
char getChoice(char h, char w, char b, char f, char q);

int main()
{

    char border = '#', fill = '*', choice;
    int newHeight = 0;
    int newWidth = 0;
    char newBorder = (char)0;
    char newFill = (char)0;
    int height = 10, width = 10;
    cout << endl << "Welcome! \n";
    while (true)
    {
        drawRectangle(height, width, border, fill);

        cout << endl << "Choose from the following: \n";
        displayChoices();
        choice = getChoice(H, W, B, F, Q);
        //if height is changed, update height. If width is changed, update width of rect.
        //if border is changed, update rectangle border. If fill is changed, update rectangle fill
        switch (choice)
        {
        case Q:
                return 0;

        case H:
                cout << "Enter new height between " << MIN_HEIGHT << " and " << MAX_HEIGHT << ": \n";
                cin >> newHeight;
                while ((newHeight < MIN_HEIGHT) || (newHeight > MAX_HEIGHT)) {

                    cout << "That number is not in range. Try again.\n";
                    cout << "Enter a number between " << MIN_HEIGHT
                        << " and " << MAX_HEIGHT << ": ";
                    cin >> newHeight;

                }
                height = newHeight;
                break;

        case W:
                cout << "Enter new width  between " << MIN_WIDTH << " and " << MAX_WIDTH << ": \n";
                cin >> newWidth;
                while ((newWidth < MIN_WIDTH) || (newWidth > MAX_WIDTH)) {

                    cout << "That number is not in range. Try again.\n";
                    cout << "Enter a number between " << MIN_WIDTH
                        << " and " << MAX_WIDTH << ": ";
                    cin >> newWidth;

                } 
                width = newWidth;
                break;
        case B:
                cout << "Enter new border character: \n";
                cin >> newBorder;
                border = newBorder;
                break;
        case F:
                cout << "Enter new fill character: \n";
                cin >> newFill;
                fill = newFill;
                break;
        }
    }
    return 0;
}

//draws rectangle
void drawRectangle(int row, int col, char border, char fill)
{
    for (int i = 0; i < row; i++) {
        for (int j = 0; j < col; j++) {
            if ((i == 0) || (i == (row - 1)) || (j == 0) || (j == (col - 1))) {
                cout << border;
            }
            else {
                cout << fill;
            }
        }
        cout << endl;
    }
}

//diplays users choices between height, width
//border and quit
void displayChoices()
{
    cout << "h) Change the height.\n";
    cout << "w) Change the width.\n";
    cout << "b) Change the border character.\n";
    cout << "f) Change the fill character.\n";
    cout << "q) Quit program.\n";
}

//takes users choice and asks for the new value or character 
char getChoice(char h, char w, char b, char f, char q) {
    char choice, newBorder, newFill;
    int newHeight, newWidth, count = 0;

    cin >> choice;

    while ((choice != h && choice != w && choice != b && choice != f && choice != q)) {
        cout << "Not a valid choice. Choose again.\n";
        cin >> choice;
    }
    return choice;


}