如何用c++和QT写一个闪闪得爱心？

首先建议在QT中创建一个QWidget窗口，然后使用C语言绘制爱心。

以下是一个简单的C程序，用于绘制一个闪闪得爱心：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define SIZE 100
#define PI 3.14159265358979323846

int main()
{
    int i, j, n;
    double x, y;
    char heart[SIZE][SIZE] = {' '};

    printf("Enter the size of the heart:");
    scanf("%d", &n);

    for (i = 0; i <= 2 * n; i++)
    {
        for (j = 0; j <= 2 * n; j++)
        {
            x = (double)(j - n) / n;
            y = (double)(n - i) / n;
            if (pow(x, 2) + pow(y, 2) <= 1)
            {
                if (pow(x - 0.5, 2) + pow(y, 2) <= 0.25 || pow(x + 0.5, 2) + pow(y, 2) <= 0.25)
                {
                    heart[i][j] = '*';
                }
            }
        }
    }

    for (i = 0; i <= 2 * n; i++)
    {
        for (j = 0; j <= 2 * n; j++)
        {
            printf("%c", heart[i][j]);
        }
        printf("\n");
    }

    return 0;
}

然后，我们可以在QT应用程序中使用QPainter类，在一个QWidget上绘制出这个爱心。

以下是应用程序的C++代码：

#include <QtWidgets/QApplication>
#include <QtWidgets/QWidget>
#include <QtGui/QPainter>

class HeartWidget : public QWidget
{
    Q_OBJECT
public:
    HeartWidget(QWidget *parent = nullptr);

protected:
    void paintEvent(QPaintEvent *event);

private:
    int size = 100;
};

HeartWidget::HeartWidget(QWidget *parent) : QWidget(parent)
{
}

void HeartWidget::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event);

    QSize widgetSize = this->size();
    int xCenter = widgetSize.width() / 2;
    int yCenter = widgetSize.height() / 2;

    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing, true);
    painter.setRenderHint(QPainter::HighQualityAntialiasing, true);

    painter.setBrush(Qt::red);

    QPolygonF heartPolygon;
    for (int i = 0; i <= 2 * size; i++)
    {
        for (int j = 0; j <= 2 * size; j++)
        {
            double x = (double)(j - size) / size;
            double y = (double)(size - i) / size;
            if (pow(x, 2) + pow(y, 2) <= 1)
            {
                if (pow(x - 0.5, 2) + pow(y, 2) <= 0.25 || pow(x + 0.5, 2) + pow(y, 2) <= 0.25)
                {
                    QPointF point(xCenter + x * size, yCenter + y * size);
                    heartPolygon.append(point);
                }
            }
        }
    }

    painter.drawPolygon(heartPolygon);
}

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    HeartWidget widget;
    widget.resize(500, 500);
    widget.show();

    return a.exec();
}