Question

我正在尝试创建一个函数，以检查两副牌的顺序是否相同。

我编写了一个辅助功能cardEq来测试两张Card是否相同，并且可以正常工作。在deckEq函数中不起作用。

import sys
from cx_Freeze import setup, Executable

# Dependencies are automatically detected, but it might need fine tuning.
build_exe_options = {"packages": ["os"], "excludes": ["tkinter"]}

# GUI applications require a different base on Windows (the default is for a
# console application).
base = None
if sys.platform == "win64":
    base = "Win64GUI"

setup(  name = "cev",
        version = "0.1",
        description = "My CEV application!",
        options = {"build_exe": build_exe_options},
        executables = [Executable("cev.py", base=base)])

我希望它返回true或false，但是会引发错误： TypeError：无法读取未定义的属性“ suit” 在cardEq（代表：2：12）在deckEq（repl：7：8）

编辑：我将while语句中的（i <53）更改为（i <52）。感谢您抓住@Christopher和@ traktor53。我猜问题是该函数正在不存在的数组项（第52个）上调用cardEq。由于这是为了比较卡片组，因此只能使用第51个元素（第52个卡片）。

Answer 1

@Christopher推测，该问题是在deckEq内从零开始的52张卡片的阵列中检查53张卡片。将while循环语句更改为

  while (i < 52){

看到它可以在52张卡座中正常工作-

"use strict";
//Card Struct
//value 1 is ace, 11 is Jack, 12 is Queen, and 13 is King
function Card(suit, value, color){
  this.suit = suit,
  this.value = value,
  this.color = color
}

//Check if two Cards are the same
function cardEq(card1, card2){
  if(card1.suit === card2.suit
     && card1.value === card2.value
     && card1.color === card2.color){
    return true;
  } else {return false;}
}

//Check if two Decks/arrays of Cards are in the same order
function deckEq(deck1, deck2){
  let i = 0;
  let flag = false;
  while (i < 52){
    let x = deck1[i];
    let y = deck2[i];
    if(cardEq(x, y) === true){
      flag = true;
      i = i + 1;
    } else {flag = false; break;}
  }
  return flag;
}

function createDeck(){
    const deck = [];
    const colors = ["black", "red", "red", "black"];
    for( var i = 0; i < 52; ++i) {
        var suite = Math.floor( i / 13);
        var value = i % 13 + 1;
        var color = colors[ suite];
        deck.push( new Card( suite, value, color));
    }
    return deck;
}

let deck1 = createDeck();
let deck2 = createDeck();

console.log( deckEq( deck1, deck2));  // expect true
deck2[42] = deck2[0];
console.log( deckEq( deck1, deck2));  // expect false

最好还是使用卡座数组的长度来控制while循环迭代的次数，并在开始循环之前测试卡座的长度是否相同。

Answer 2

函数内部的

this仅在将函数用作“ constructor function”时才起作用，这需要构造函数生成的对象的new实例。这就是this将绑定到的对象，否则，this将绑定到window并且window没有suit属性。

//Card Struct
//value 1 is ace, 11 is Jack, 12 is Queen, and 13 is King
function Card(suit, value, color){
  this.suit = suit,
  this.value = value,
  this.color = color
}

//Check if two Cards are the same
function cardEq(card1, card2){
  if(card1.suit === card2.suit
     && card1.value === card2.value
     && card1.color === card2.color){
    return true;
  } else {return false;}
}

//Check if two Decks/arrays of Cards are in the same order
function deckEq(deck1, deck2){
  let ceq = new cardEq(x,y); // <-- Need an instance produces by the function
  let i = 0;
  let flag = false;
  while (i < 53){
    let x = deck1[i];
    let y = deck2[i];
    if(ceq === true){  // <-- Use the instance
      flag = true;
      i = i + 1;
    } else {flag = false; break;}
  }
  return flag;
}

在另一个函数中多次调用该函数会引发TypeError：无法读取未定义的属性“ suit”

2 个答案: