为什么我在Python中收到“无效的文字错误”

Question

我检查了多次，但是我不知道怎么了。

class stack:
    def __init__(self):
        self.stack=[]
        self.limit=5

    def isfull():
        if len(self.stack)==self.limit:
            return True
        else:
            return False

    def isempty():
        if len(self.stack)==0:
            return True
        else:
            return False

    def push(self,ele):
        if self.isfull():
            print("stack overflow")
        else:
            self.stack.append(ele)

    def pop(self):
        if self.isempty():
            print("stack underflow")
        else:
            print(self.stack.pop())

    def peek(self):
        if self.isempty():
            print("stack empty")
        else:
            print(self.stack[-1])

    def display(self):
        if self.isempty():
            print("stack underflow")
        else:
            for i in self.stack:
                print (i, end = " ")
            print()    
s=stack()

while True:
    print("1 2 3 4 5")
    ch=int (input("entre 12345"))

    if ch==1:
        ele=int(input("ener input"))
        s.push(ele)
    elif ch==2:
        s.pop()
    elif ch==3:
        s.peek()
    elif ch==4:
        s.display()
    else:
        print("thank you")        
        break        

Answer 1

您必须使用try / catch / else构造检查/验证输入的数据：

class Stack:
    def __init__(self):
        self.stack = []
        self.limit = 5

    def isfull(self):
        return len(self.stack) == self.limit

    def isempty(self):
        return len(self.stack) == 0

    def push(self, ele):
        if self.isfull():
            print("stack overflow")
        else:
            self.stack.append(ele)

    def pop(self):
        if self.isempty():
            print("stack underflow")
        else:
            print(self.stack.pop())

    def peek(self):
        if self.isempty():
            print("stack empty")
        else:
            print(self.stack[-1])

    def display(self):
        if self.isempty():
            print("stack underflow")
        else:
            for i in self.stack:
                print(i, end=" ")
            print()


s = Stack()

while True:
    try:
        ch = int(input('Enter a valid option [1,2,3,4,5]: '))
    except ValueError:
        print("That's not a valid number!")
    else:
        if ch == 1:
            try:
                ele = int(input('Enter a valid number: '))
            except ValueError:
                print("That's not a valid number!")
            else:
                s.push(ele)
        elif ch == 2:
            s.pop()
        elif ch == 3:
            s.peek()
        elif ch == 4:
            s.display()
        else:
            print("thank you")
            break