Question

这是Python。我正在尝试编写一个程序，要求用户输入字符串而不使用全局变量。如果字符串只有并排的括号，那么它是偶数。如果它有字母，数字或括号间隔，那么它是不均匀的。例如，（）和（）（）和（（）（））是偶数，而（（）和（pie）和（）不是。下面是我到目前为止写的。我的程序继续打印'无限地输入你的字符串，我现在仍然坚持这个问题。

selection = 0
def recursion():
#The line below keeps on repeating infinitely.
    myString = str(input("Enter your string: "))
    if not myString.replace('()', ''):
        print("The string is even.")
    else:
        print("The string is not even.")

while selection != 3:
    selection = int(input("Select an option: "))

    #Ignore this.
    if selection == 1:
        print("Hi")

    #This won't work.
    elif selection == 2:
        def recursion():
            recursion()

Answer 1

这会输出正确的偶数/不均匀答案。

 selection = 0
 def recursion():
    myString = str(raw_input("Enter your string: "))  #Use raw_input or ( ) will be () 
    paren = 0
    for char in myString:
        if char == "(":
            paren += 1
        elif char == ")":
            paren -= 1
        else:
            print "Not Even"
            return

        if paren < 0:
            print "Not even"
            return
    if paren != 0:
        print "Not even"
        return
    print "Even"
    return

while selection != 3:
    selection = int(input("Select an option: "))

    #Ignore this.
    if selection == 1:
        print("Hi")

    #This won't work.
    elif selection == 2:
        recursion()    #This isn't a recursive function - naming it as so is...

Answer 2

除非你使用的是Python 3，否则你应该使用raw_input而不是input，因为输入会以最适合输入的类型返回结果，而raw_input总是返回一个字符串。在Python 3中，输入始终返回一个字符串。另外，为什么要重新定义递归？只需从elif语句中调用它即可。例如：

selection = 0
def recursion():
#The line below keeps on repeating infinitely.
    myString = raw_input("Enter your string: ") # No need to convert to string.
    if not myString.replace('()', ''):
        print("The string is even.")
    else:
        print("The string is not even.")

while selection != 3:
    selection = int(raw_input("Select an option: "))

    #Ignore this.
    if selection == 1:
        print("Hi")

    #This won't work.
    elif selection == 2:
        recursion() # Just call it, as your program already
                    # recurs because of the if statement.

制作圆括号计划？我被卡住了

2 个答案: