$.each(selections, function (k, v) { if (v[keyName]) { keys.push(v[keyName]); } }); return keys; 什么意思

这段代码使用 jQuery 的 $.each 函数遍历一个名为 selections 的数组，该数组中的每个元素都是一个 JavaScript 对象。在每次遍历时，判断当前元素的 keyName 属性是否存在，如果存在则将其值加入到一个名为 keys 的数组中。最后返回这个数组。简而言之，这段代码的目的是提取 selections 数组中每个对象的 keyName 属性的值，并返回这些值组成的数组。

相关问题

$table.on('check.bs.table uncheck.bs.table ' + 'check-all.bs.table uncheck-all.bs.table', function () { $remove.prop('disabled', !$table.bootstrapTable('getSelections').length) // save your data, here just save the current page selections = getIdSelections() // push or splice the selections if you want to save all data selections }) $table.on('all.bs.table', function (e, name, args) { console.log(name, args) })

这段代码是用于监听表格的选择事件。当用户选中或取消选中一个或多个行，或者全选或取消全选时，会触发相应的事件。在事件处理函数中，首先根据当前选中的行数来禁用或启用一个按钮（$remove），然后保存当前页的选中数据（selections = getIdSelections()）。另外，代码中还添加了一个监听所有表格事件的处理函数，它会在任何表格事件触发时打印事件名和参数。

请注意，这段代码中的 $table 和 $remove 变量是通过 jQuery 或类似库选择相应元素后得到的。getIdSelections() 函数是自定义函数，用于获取当前选中行的数据。如果想要保存所有数据的选中项，可以根据需要进行相应的操作（如推入或剔除选中项）。

1、Experiment purpose (1)Write the txt file. (2)Class definition. (3)Function application. (4)Selections. (5)Loops 2、Experiment task Project 1: Define the Rectangle2D class that contains: Two double data fields named x and y that specify the center of the rectangle with constant get functions and set functions. (Assume that the rectangle sides are parallel to x- or y-axes.) The double data fields width and height with constant get functions and set functions. A no-arg constructor that creates a default rectangle with (0, 0) for (x, y) and 1 for both width and height. A constructor that creates a rectangle with the specified x, y, width, and height. A constant function getArea() that returns the area of the rectangle. A constant function getPerimeter() that returns the perimeter of the rectangle. A constant function contains(double x, double y) that returns true if the specified point (x, y) is inside this rectangle. See Figure a. A constant function contains(const Rectangle2D &r) that returns true if the specified rectangle is inside this rectangle. See Figure b. A constant function overlaps(const Rectangle2D &r) that returns true if the specified rectangle overlaps with this rectangle. See Figure c. Draw the UML for the class. Implement the class. Write a test program that creates three Rectangle2D objects r1(2, 2, 5.5, 4.9), r2(4, 5, 10.5, 3.2)), and r3(3, 5, 2.3, 5.4), and displays r1’s area and perimeter, and displays the result of r1.contains(3, 3), r1.contains(r2), and r1.overlaps(r3). And save all these results in the txt file that is called Result.txt.写一段c++代码

下面是C++代码实现：

#include <iostream>
#include <fstream>

using namespace std;

class Rectangle2D {
private:
double x, y;
double width, height;
public:
Rectangle2D() {
x = y = 0;
width = height = 1;
}
Rectangle2D(double x, double y, double width, double height) {
this->x = x;
this->y = y;
this->width = width;
this->height = height;
}
double getX() const {
return x;
}
double getY() const {
return y;
}
double getWidth() const {
return width;
}
double getHeight() const {
return height;
}
void setX(double x) {
this->x = x;
}
void setY(double y) {
this->y = y;
}
void setWidth(double width) {
this->width = width;
}
void setHeight(double height) {
this->height = height;
}
double getArea() const {
return width * height;
}
double getPerimeter() const {
return 2 * (width + height);
}
bool contains(double x, double y) const {
return abs(x - this->x) <= width / 2 && abs(y - this->y) <= height / 2;
}
bool contains(const Rectangle2D& r) const {
return contains(r.getX() - r.getWidth() / 2, r.getY() - r.getHeight() / 2) &&
contains(r.getX() + r.getWidth() / 2, r.getY() + r.getHeight() / 2);
}
bool overlaps(const Rectangle2D& r) const {
return abs(x - r.getX()) <= (width + r.getWidth()) / 2 &&
abs(y - r.getY()) <= (height + r.getHeight()) / 2;
}
};

int main() {
Rectangle2D r1(2, 2, 5.5, 4.9);
Rectangle2D r2(4, 5, 10.5, 3.2);
Rectangle2D r3(3, 5, 2.3, 5.4);

ofstream outFile("Result.txt"); // 打开文件

if (outFile.is_open()) {
outFile << "r1's area: " << r1.getArea() << endl;
outFile << "r1's perimeter: " << r1.getPerimeter() << endl;
outFile << "r1 contains (3, 3): " << (r1.contains(3, 3) ? "true" : "false") << endl;
outFile << "r1 contains r2: " << (r1.contains(r2) ? "true" : "false") << endl;
outFile << "r1 overlaps r3: " << (r1.overlaps(r3) ? "true" : "false") << endl;

outFile.close(); // 关闭文件
} else {
cout << "Unable to open file" << endl;
}

return 0;
}

运行完毕后，会在当前目录下生成一个名为Result.txt的文件，里面包含了程序输出的结果。