c++ - 使用结构器创建一个太空船对象数组

Question

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

struct SpaceShip
{
    int x_coordinate = (rand()%2000) + 1;
    int y_coordinate = (rand()%2000) + 1;
};

SpaceShip updateSpaceShip ()
{
    SpaceShip ship;
    ship.x_coordinate += 100;
    ship.y_coordinate +=100;

    return ship;
}

int main()
{
    SpaceShip ship = updateSpaceShip();
    srand(time(NULL));
    if ((ship.x_coordinate > 1024 && ship.y_coordinate > 768) || (ship.y_coordinate > 1024 && ship.x_coordinate > 768))
    {
        cout << "Ship out of range" << endl;
    }
    else
    {
        cout << "Ship in range" << endl;
    }

    return 0;
}

问题问；创建一个宇宙飞船对象数组并编写一个程序，不断更新它们的位置，直到它们全部离开屏幕。假设屏幕尺寸为 1024 像素 x 768 像素。

我对这个有点困惑。我正在学习的电子书没有涵盖课程，所以我想我不应该使用它们。我的查询是 x 和 y 坐标甚至更新，或者我应该放入 while 循环或 for 循环以保持更新。

Answer 1

假设您不允许使用构造函数：

struct SpaceShip
{
    int x_coordinate;
    int y_coordinate;
    bool isOnScreen;
};

int main() {

    int const NumberOfShips = 10;
    int const ScreenWidth = 1024;
    int const ScreenHeight = 768;

    srand(time(NULL));
    SpaceShip Ships[ NumberOfShips ];
    for( int i = 0; i < NumberOfShips; ++i ) {
        Ships[ i ].x_coordinate = rand() * ScreenWidth / RAND_MAX;
        Ships[ i ].y_coordinate = rand() * ScreenHeight / RAND_MAX;
        Ships[ i ].isOnScreen = true;
    };

    int NumberOfShipsOnScreen = NumberOfShips;
    while( NumberOfShipsOnScreen > 0 ) {

        for( int i = 0; i < NumberOfShips; ++i ) {

            if( !Ships[ i ].isOnScreen ) {
                continue;
            }

            Ships[ i ].x_coordinate += 100;
            Ships[ i ].y_coordinate += 100;

            if( Ships[ i ].x_coordinate > 1024 || Ships[ i ].y_coordinate > 768 ) {
                Ships[ i ].isOnScreen = false;
                --NumberOfShipsOnScreen;
            }
        }
    }
};

Answer 2

/* 

Create an array of space ship objects and write a program that continually updates their
positions, when ship go off the screen then it reset its position.

*/

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;
void srand(unsigned int t);
struct Space_ship
{
    int x_co_ordinate;
    int y_co_ordinate;
};

Space_ship Get_new_ship(Space_ship ship);
Space_ship Update_space_ship(Space_ship ship);

int rand_range(int low, int high);

int main()
{   srand(time(NULL));
    Space_ship ship[5];
    for(int i=0;i<5;i++)
    {
        ship[i] = Get_new_ship(ship[i]);
    }
    while(1)
    {
        for(int i=0;i<5;i++)
        {
            ship[i] = Update_space_ship(ship[i]);
        }
        for(int i=0;i<5;i++)
           {
           if(ship[i].x_co_ordinate < 1024 && ship[i].y_co_ordinate < 768)
            {
            cout<<"ship "<<i+1<<" : "<<"x = "<<ship[i].x_co_ordinate<<"     ,     "<<"y = "<<ship[i].y_co_ordinate<<endl<<endl;
            }
            else
            {
                cout<<"ship "<<i+1<<" is out of scope "<<endl<<endl;
                ship[i] = Get_new_ship(ship[i]);
            }
        for(int i=0;i<50000000;i++)   //delay
            {
                ; // do nothing
            }

            }
    }

    return 0;
}

int rand_range(int low, int high)
{
    int num ;
    while(1)
    {
        num = rand();
        if (num>=low && num<= high)
        {
        return num;
        }
    }
}

Space_ship Get_new_ship(Space_ship ship)
{

    ship.x_co_ordinate = rand_range(0,1024);
    ship.y_co_ordinate = rand_range(0,768);
    return ship;
}

Space_ship Update_space_ship(Space_ship ship)
{
    ship.x_co_ordinate += 100;
    ship.y_co_ordinate += 78;
    return ship;
}