Question

这是我的代码，这是一款棋盘游戏。我不知道为什么我会收到这个错误：

TypeError：“NoneType”类型的参数不可迭代。

问题出现在move_tiger()函数中，但我在move_goat()函数中使用了相同的代码，它运行正常。有人可以告诉我这个错误在我的情况下意味着什么，因为我不认为我试图迭代move_tiger()函数中的任何内容。谢谢你的帮助。

class Board:

    def __init__(self): 
        self.board = dict()
        # a, b, c, d, and e are keys
        self.board['a'] = ['T']
        self.board['b'] = ['0','T','0','0','T','0']
        self.board['c'] = ['0','0','0','0','0','0']
        self.board['d'] = ['0','0','0','0','0','0']
        self.board['e'] = ['0','0','0','0']
        self.phase = 'add'
        self.numgoats = 0

    def print_board(self):
        for letter in 'abcde':
            for vertex in self.board[letter]:
                print vertex,
            print

    def content(self, position):
        row=list(position)[0]
        column=list(position)[1]
        return self.board[row][int(column)]

    def _set(self, position, value):
        self.board[position[0]][position[1]] = value

    def neighbors(self, position):
        if position == ('a',0):
            return [('b',1),('b',2),('b',3),('b',4)]
        # bunch of extraneous elif's that all return something skipped
        elif position == ('e',3):
            return [('e',2),('d',4)]

    def add_goat(self, position):
        if self.phase == 'add':
            if self.content(position) == '0':
                self._set(position, 'G')
                self.numgoats+=1
                if self.numgoats==3:
                    self.phase = 'move'

    def move_goat(self, old, new):
        if self.phase!='move':
            print "invalid move; try again"
        elif self.content(old) == 'G' and self.content(new) == '0' and new in self.neighbors(old):
            self.board[old[0]][old[1]] = '0'
            self.board[new[0]][new[1]] = 'G'
        else:
            print "invalid move; try again"

    def move_tiger(self, old, new):
        if self.content(old) == 'T' and self.content(new) == '0' and new in self.neighbors(old):
                self.board[old[0]][old[1]] = '0'
                self.board[new[0]][new[1]] = 'T'
        else:
            print "invalid move; try again"


myboard = Board()
myboard.print_board()
myboard.add_goat(('b',0))
myboard.print_board()
myboard.add_goat(('c',0))
myboard.print_board()
myboard.add_goat(('d',0))
myboard.print_board()
myboard.move_goat(('c',0),('c',1))
myboard.print_board()
myboard.move_goat(('c',1),('b',5))
myboard.print_board()
myboard.move_tiger(('b',4),('b',3))
myboard.print_board

此代码生成以下内容：

T
0 T 0 0 T 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0
T
G T 0 0 T 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0
T
G T 0 0 T 0
G 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0
T
G T 0 0 T 0
G 0 0 0 0 0
G 0 0 0 0 0
0 0 0 0
T
G T 0 0 T 0
0 G 0 0 0 0
G 0 0 0 0 0
0 0 0 0
invalid move; try again
T
G T 0 0 T 0
0 G 0 0 0 0
G 0 0 0 0 0
0 0 0 0
Traceback (most recent call last):
  File "game2.py", line 110, in <module>
    myboard.move_tiger(('b',4),('b',3))
  File "game2.py", line 91, in move_tiger
    if self.content(old) == 'T' and self.content(new) == '0' and new in self.neighbors(old):
TypeError: argument of type 'NoneType' is not iterable

Answer 1

在Python中，所有函数（和方法）都隐式返回None，除非它们在执行期间到达显式return语句。您的neighbours方法似乎收到position任何if-elif分支未涵盖的else。

尝试在neighbours中添加position分支，以便您可以看到意外的def neighbors(self, position): if position == ('a',0): return [('b',1),('b',2),('b',3),('b',4)] elif position[0] == ('b',0): return [('b',1),('c',0),('c',1)] # ... else: raise ValueError(position)：

public enum Language {
    English=1,
    Telugu=2,
    Hindi=3,
    Spanish=4
}

Answer 2

当("b", 4)值为self.neighbors(old)时会发生异常，因为None会返回neighbors。我不确定是否完全理解您的代码的作用，但也许您应该检查一下<?php if (isset($_POST['send'])) { require_once JPATH_BASE . '/includes/config.php'; $firstname = $_POST['firstname']; $fathername = $_POST['fathername']; $grandfathername = $_POST['grandfathername']; $familyname = $_POST['familyname']; $sql = "INSERT INTO subventions (firstname,fathername,grandfathername,familyname) VALUES ('$firstname','$fathername','$grandfathername','$familyname')"; $inser = mysqli_query($con,$sql); echo '<script type="text/javascript"> alert("sent"); </script>'; mysqli_close($inser); } ?>方法是否错过了一个案例。

“TypeError：'NoneType'类型的参数不可迭代”？

2 个答案: