你能帮我解决以下问题吗
我试图从用户那里获得一个字符串输入,然后将字符串推入堆栈机,以检查字符串的有效性。如果字符串通过了定义的规则,那么将检查StackMachine的输出字符串是否为回文..这就是我到目前为止所尝试的
注意您只能使用StackMachine类中的函数,而不能使用其他方法来确定字符串的有效性。接受字符串的条件是您已读取所有输入字符串,并且堆栈为空
```
class StackMachine(object):
SMRules = {} # dictionary of SM rules
def __init__(self):
self.Stack = ['S'] # populate stack with initial 'S'
self.size = 1 # set size of stack to 1
self.SMRules = {} # Place rules here
def pop(self):
if len(self.Stack) <1:
pass
else:
self.Stack.pop(0)
self.size-= 1 # reduce stack size by 1
return
def peek(self):
ss = ""
if len(self.Stack) < 1:
return ""
else:
ss = self.Stack
return ss[0]
def stackIsEmpty(self):
if len(self.Stack) == 0:
return True
else:
return False
def push(self,str):
sStr = str[::-1] # slicing
for chr in sStr:
self.Stack.insert(0,chr) # push string onto top of stack
self.size = len(self.Stack)
return
def printStack(self):
print("Stack: [",end='')
for item in self.Stack:
print(item,end='')
print("]")
return
def printRules(self):
print("SM Rules:")
rn = 1
for key, value in self.SMRules.items():
print("Rule",rn,"%4s" % key,"|", value)
rn += 1
return
def main():
Stk = StackMachine()
text =str(input('Please enter the string: '))
for character in text:
Stk.push(character)
reversed_text = ''
while not Stk.stackIsEmpty():
reversed_text = reversed_text + Stk.pop()
if text == reversed_text:
print('The string is a palindrome.')
else:
print('The string is not a palindrome.')
if __name__ == '__main__':
main()
Am getting the following Error and i dont know how to solve it
```
File "C:\Users\user\Stack-Machine\StackMachine.py", line 91, in main
reversed_text = reversed_text + Stk.pop()
TypeError: can only concatenate str (not "NoneType") to str`enter code here`
我的问题是 1.如何解决错误? 2.如何从stackMachine按字符打印字符串字符 3.成功检查堆栈计算机处理的字符串是否为回文
根据定义,
StackMachine.pop()
返回None
当您执行
reversed_text + Stk.pop()
时,即使reversed_text
是一个字符串,Stk.pop()
是None
,这会导致您看到的TypeError
为什么需要使用所谓的
StackMachine
类来检查字符串是否是回文?有更简单的方法来检查字符串是否是回文如果您只想获得一个字符串输入并确定它是否是回文,您可以这样做:
相关问题 更多 >
编程相关推荐