Typescript - 多维数组初始化
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Typescript - multidimensional array initialization
提问by Fka
I'm playing with Typescript and I wonder, how to properly instantiate and declare multidimensional array. Here's my code:
我正在使用 Typescript，我想知道如何正确实例化和声明多维数组。这是我的代码：
class Something {
private things: Thing[][];
constructor() {
things = [][]; ??? how instantiate object ???
for(var i: number = 0; i < 10; i++) {
this.things[i] = new Thing[]; ??? how instantiate 1st level ???
for(var j: number = 0; j< 10; j++) {
this.things[i][j] = new Thing(); ??? how instantiate 2nd lvl item ???
}
}
}
}
Can you give me any hint about selected places?
你能给我一些关于选定地点的提示吗？
回答by Puppy
You only need []to instantiate an array - this is true regardless of its type. The fact that the array is of an array type is immaterial.
您只需要[]实例化一个数组 - 无论其类型如何，都是如此。数组是数组类型这一事实并不重要。
The same thing applies at the first level in your loop. It is merely an array and []is a new empty array - job done.
同样的事情适用于循环的第一级。它只是一个数组，[]是一个新的空数组 - 工作完成。
As for the second level, if Thingis a class then new Thing()will be just fine. Otherwise, depending on the type, you may need a factory function or other expression to create one.
至于第二层，如果Thing是一个班级new Thing()就可以了。否则，根据类型，您可能需要一个工厂函数或其他表达式来创建一个。
class Something {
private things: Thing[][];
constructor() {
this.things = [];
for(var i: number = 0; i < 10; i++) {
this.things[i] = [];
for(var j: number = 0; j< 10; j++) {
this.things[i][j] = new Thing();
}
}
}
}
回答by RMuesi
If you want to do it typed:
如果你想这样做，请输入：
class Something {
areas: Area[][];
constructor() {
this.areas = new Array<Array<Area>>();
for (let y = 0; y <= 100; y++) {
let row:Area[] = new Array<Area>();
for (let x = 0; x <=100; x++){
row.push(new Area(x, y));
}
this.areas.push(row);
}
}
}
回答by techguy2000
Here is an example of initializing a boolean[][]:
下面是一个初始化 boolean[][] 的例子：
const n = 8; // or some dynamic value
const palindrome: boolean[][] = new Array(n).fill(false).map(() => new Array(n).fill(false));
回答by Pipo
Beware of the use of push method, if you don't use indexes, it won't work!
小心使用push方法，不使用索引是不行的！
var main2dArray: Things[][] = []
main2dArray.push(someTmp1dArray)
main2dArray.push(someOtherTmp1dArray)
gives only a 1 line array!
只给出一个 1 线阵列！
use
用
main2dArray[0] = someTmp1dArray
main2dArray[1] = someOtherTmp1dArray
to get your 2d array working!!!
让你的二维数组工作！！！
Other beware! foreach doesn't seem to workwith 2d arrays!
其他小心！foreach 似乎不适用于二维数组！
