c++ - 如何在C++中画一个带星星的圆圈？

Question

我是 C++ 新手，正在做一道练习题。 我做了什么:

for (int i = 0; i < 2 * r; i++) {
    for (int j = 0; j < 2 * r; j++) {
        if (i == sqrt((static_cast<int> (r))^2 - j^2)) {
            cout << "*";
        } else {
            cout << " ";
        }
    }
    cout << endl;
}

然而，它并没有吸引我任何东西。 :(

Answer 1

下面的代码是一种绘制圆的简单方法，无需使用花哨的函数跳转到任意选择的 x 或 y 位置。

#include <iostream>
#include <math.h>

using namespace std;

int pth (int x,int y)  {
    return sqrt (pow(x,2)+pow(y,2));
 }

int main ( )  {

    int c=0;
    int r=10;

    const int width=r;
    const int length=r*1.5;

    for (int y=width;y >= -width;y-=2)  {
        for (int x=-length;x <= length;x++)  {

            if ((int) pth(x,y)==r) cout << "*";
            else cout << " ";

         }
         cout << "\n";
     }
     cin.get();

return 0;
 }

如果您想要更高级的代码并且您使用的是 Windows 平台并且您使用 Visual Studio 创建程序，那么下面的代码将会很有趣。

它使用像 SetConsoleCursorPosition() 这样的函数来设置 x 和 y 位置，使用 SetConsoleTextAttribute() 来设置颜色。代码在控制台文本窗口中绘制线、像素、矩形和圆。

#include<stdio.h>
#include <iostream>
#include <stdio.h>
#include <math.h>
#include <time.h>
#include <windows.h>

using namespace std;

void gotoxy(int x, int y);
void setcolor(WORD color);
void setForeGroundAndBackGroundColor(int ForeGroundColor,int BackGroundColor);
void clearscreen();
void drawpixel( unsigned char x, unsigned char y, unsigned char Color);
void drawpixel2( unsigned char x, unsigned char y, unsigned char Color, char character);
void drawcircle(int x, int y, int a, int b, int color);
void drawline(int x0, int y0, int x1, int y1, int color);
void drawfilledrectangle(unsigned char x1,unsigned char y1,unsigned char x2,unsigned char y2,unsigned char bkcol);
void drawframe(unsigned x,unsigned y,unsigned sx,unsigned sy,unsigned char col,unsigned char col2,char text_[]);
void drawwindow(unsigned x,unsigned y,unsigned sx,unsigned sy,unsigned char col,unsigned char col2,unsigned char bkcol,char text_[]);
void drawcolorpalette();



int main(void){

    setcolor(15);
    clearscreen();
    drawwindow(3,2,77,15,31,31,31,"a window is drawn");

    int X = 40;
    int Y = 12;
    int rad = 8;
    int col = 15;
    double deg = 0;

    // draw a circle using sin( ) and cos( )
    do {
         X = (int) (rad * cos(deg));
         Y = (int) (rad * sin(deg));
         drawpixel2 (40+X, 12+Y,  col, '*' );
         deg +=  0.005;
    }   while (deg <= 6.4);




    drawcircle(60, 10, 8, 8, 15);

    drawline(1,1,77,22,15);

    gotoxy(40,4);
    cout<<"Another circle is drawn.";


    gotoxy(60,22);
    cout<<"A Line is drawn.";

    gotoxy(20,13);
    cout<<"A circle is drawn.";



    setcolor(7);
    gotoxy(1,23);
    cin.ignore();
    cin.get();

return 0;
}


//*****************************************************************************

void gotoxy(int x, int y){
    COORD coord;
    coord.X = x; coord.Y = y;
    SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
    return;
}

//*****************************************************************************

void setcolor(WORD color){
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),color);
    return;
}


//
//     colors:
//     0 = Black
//     1 = Blue
//     2 = Green
//     3 = Cyan
//     4 = Red
//     5 = Magenta
//     6 = Yellow
//     7 = LightGray
//     8 = DarkGray
//     9 = LightBlue
//     10 = LightGreen
//     11 = LightCyan
//     12 = LightRed
//     13 = LightMagenta
//     14 = LightYellow
//     15 = White


//

//*****************************************************************************

void setForeGroundAndBackGroundColor(int ForeGroundColor,int BackGroundColor){
   int color=16*BackGroundColor+ForeGroundColor;
   setcolor(color);
}

//*****************************************************************************

void clearscreen(){
    COORD coordScreen = { 0, 0 };
    DWORD cCharsWritten;
    CONSOLE_SCREEN_BUFFER_INFO csbi;
    DWORD dwConSize;
    HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);

    GetConsoleScreenBufferInfo(hConsole, &csbi);
    dwConSize = csbi.dwSize.X * csbi.dwSize.Y;
    FillConsoleOutputCharacter(hConsole, TEXT(' '), dwConSize, coordScreen, &cCharsWritten);
    GetConsoleScreenBufferInfo(hConsole, &csbi);
    FillConsoleOutputAttribute(hConsole, csbi.wAttributes, dwConSize, coordScreen, &cCharsWritten);
    SetConsoleCursorPosition(hConsole, coordScreen);
    return;
}

//*****************************************************************************

void drawpixel( unsigned char x, unsigned char y, unsigned char Color){
        setcolor(Color);
        gotoxy(x,y);printf("Û");
}

//*****************************************************************************

void drawpixel2( unsigned char x, unsigned char y, unsigned char Color, char character){
        setcolor(Color);
        gotoxy(x,y);printf("%c",character);
}

//*****************************************************************************

void drawcircle(int x, int y, int a, int b, int color){
    int wx, wy;
    int thresh;
    int asq = a * a;
    int bsq = b * b;
    int xa, ya;

    drawpixel(x, y+b, color);
    drawpixel(x, y-b, color);

    wx = 0;
    wy = b;
    xa = 0;
    ya = asq * 2 * b;
    thresh = asq / 4 - asq * b;

    for (;;) {
        thresh += xa + bsq;

        if (thresh >= 0) {
            ya -= asq * 2;
            thresh -= ya;
            wy--;
        }

        xa += bsq * 2;
        wx++;

        if (xa >= ya)
          break;


        drawpixel(x+wx, y-wy, color);
        drawpixel(x-wx, y-wy, color);
        drawpixel(x+wx, y+wy, color);
        drawpixel(x-wx, y+wy, color);
    }

    drawpixel(x+a, y, color);
    drawpixel(x-a, y, color);

    wx = a;
    wy = 0;
    xa = bsq * 2 * a;

    ya = 0;
    thresh = bsq / 4 - bsq * a;

    for (;;) {
        thresh += ya + asq;

        if (thresh >= 0) {
            xa -= bsq * 2;
            thresh = thresh - xa;
            wx--;
        }

        ya += asq * 2;
        wy++;

        if (ya > xa)
          break;

        drawpixel(x+wx, y-wy, color);
        drawpixel(x-wx, y-wy, color);
        drawpixel(x+wx, y+wy, color);
        drawpixel(x-wx, y+wy, color);
    }
}

//*****************************************************************************

void drawline(int x0, int y0, int x1, int y1, int color){
    int pix = color;
    int dy = y1 - y0;
    int dx = x1 - x0;
    int stepx, stepy;

    if (dy < 0) { dy = -dy;  stepy = -1; } else { stepy = 1; }
    if (dx < 0) { dx = -dx;  stepx = -1; } else { stepx = 1; }
    dy <<= 1;                                                  // dy is now 2*dy
    dx <<= 1;                                                  // dx is now 2*dx

  drawpixel( x0, y0,pix);
    if (dx > dy) {
        int fraction = dy - (dx >> 1);                         // same as 2*dy - dx
        while (x0 != x1) {
            if (fraction >= 0) {
                y0 += stepy;
                fraction -= dx;                                // same as fraction -= 2*dx
            }
            x0 += stepx;
            fraction += dy;                                    // same as fraction -= 2*dy
            drawpixel( x0, y0,pix);
        }
    } else {
        int fraction = dx - (dy >> 1);
        while (y0 != y1) {
            if (fraction >= 0) {
                x0 += stepx;
                fraction -= dy;
            }
            y0 += stepy;
            fraction += dx;
            drawpixel( x0, y0,pix);
        }
    }
}

//*****************************************************************************


void drawframe(unsigned x,unsigned y,unsigned sx,unsigned sy,unsigned char col,unsigned char col2,char text_[])
{  
    unsigned i,j,m;
    {

       m=(sx-x);                       //differential
       j=m/8;                          //adjust
       j=j-1;                          //more adjustment
       gotoxy(x,y);printf("É");       //Top left corner of box
       gotoxy(sx,y);printf("»");      //Top right corner of box
       gotoxy(x,sy);printf("È");      //Bottom left corner of box
       gotoxy(sx,sy);printf("¼");     //Bottom right corner of box

       for (i=x+1;i<sx;i++)
       {
          gotoxy(i,y);printf("Í");     // Top horizontol line
          gotoxy(i,sy);printf("Í");    // Bottom Horizontal line
       }

       for (i=y+1;i<sy;i++)
       {
          gotoxy(x,i);printf("º");     //Left Vertical line
          gotoxy(sx,i);printf("º");    //Right Vertical Line
       }

          gotoxy(x+j,y);printf(text_); //put Title
          gotoxy(1,24);
    }
}

 //*****************************************************************************

void drawfilledrectangle(unsigned char x1,unsigned char y1,unsigned char x2,unsigned char y2,unsigned char bkcol)
{
    int x,y;
    setcolor(bkcol);                       //Set to color bkcol

    for (y=y1;y<y2;y++)                    //Fill Y Region Loop
    {
        for (x=x1;x<x2;x++)               //Fill X region Loop
        {
          gotoxy(x,y);printf(" ");       //Draw Solid space
        }
    }
}

//*****************************************************************************

void drawwindow(unsigned x,unsigned y,unsigned sx,unsigned sy,
         unsigned char col, unsigned char col2,unsigned char bkcol,char text_[])
{
    drawfilledrectangle(x,y,sx,sy,bkcol);
    drawframe(x,y,sx,sy,col,col2,text_);
}

void drawcolorpalette()
{
    for (int i=0;i<16;i++)
    {
        for (int j=0;j<16;j++)
        {
            setForeGroundAndBackGroundColor(i,j);
            gotoxy(i*4,j);printf("%d",(i*j)+1);


        }

    }

}