Question

我试图让这个简单的代码只接受来自（0,100）的整数和数字。我不想使用循环来验证我的输入，并希望它们仅以＆＃34;无效输入＆＃34;退出。我坚持使用这个部分，因为当我没有有效的输入时，我似乎无法退出而没有（＆＃34; Letter等级：＆＃34;）部分...当我输入字母时，该消息不会出现。

这是我到目前为止所做的事情......我是初学者，所以如果有人可以帮助我，那就太好了。）

def convert_grade_to_letter(number_grade):
    letter_grade = ''


    if number_grade >= 90 and number_grade <= 100:
        letter_grade = 'A'
    elif number_grade >= 80:
        letter_grade = 'B'
    elif number_grade >= 70:
        letter_grade = 'C'
    elif number_grade >= 60:
        letter_grade = 'D'
    elif number_grade < 60 and number_grade >= 0:
        letter_grade = 'F'
    else:
        print("invalid input")
    return letter_grade

def main():
    number_grade = int(input("Input number grade: "))
    letter_grade = convert_grade_to_letter(number_grade)
    print("Letter grade: " + letter_grade)

main()

Answer 1

考虑捕获ValueError异常以验证您的成绩，包括整数验证和0-100范围验证：

try:
    number_grade = int(input("Input number grade: "))
    is_valid = 0 <= number_grade <= 100
    if not is_valid:
        raise ValueError("Number grade is not in the 0-100 range.")

    letter_grade = convert_grade_to_letter(number_grade)
    print("Letter grade: " + letter_grade)

except ValueError:
    print("Could not parse grade")

Answer 2

在循环中清理输入是要走的路。这样，您只能为您的功能提供正确的数据（始终清理用户输入 - 它们太有创意）：

def convert_grade_to_letter(number_grade):
    letter_grade = '' 

    if number_grade >= 90:  # not needed: and number_grade <= 100:
        letter_grade = 'A'
    elif number_grade >= 80:
        letter_grade = 'B'
    elif number_grade >= 70:
        letter_grade = 'C'
    elif number_grade >= 60:
        letter_grade = 'D'
    else:  # not needed: - if number_grade < 60 and number_grade >= 0:
        letter_grade = 'F'

    return letter_grade

def main():
    while True:  # loop until the value is between 0 and 100 and a valid int
        try:
            number_grade = int(input("Input number grade: "))
            if 0 < number_grade <= 100:
                 break
        except ValueError:
            print("Invalid Input - 1 to 100 allowed")

    letter_grade = convert_grade_to_letter(number_grade)
    print("Letter grade: " + letter_grade)

main()

如果不使用循环是一些不完整的限制，返回一个指示器，允许程序检查解析是否成功：

def convert_grade_to_letter(number_grade):
    letter_grade = ''

    if number_grade >= 90 and number_grade <= 100:
        letter_grade = 'A'
    elif number_grade >= 80:
        letter_grade = 'B'
    elif number_grade >= 70:
        letter_grade = 'C'
    elif number_grade >= 60:
        letter_grade = 'D'
    elif number_grade < 60 and number_grade >= 0:
        letter_grade = 'F'
    else:
        print("invalid input")
        return None  # check for None, only print if not None

    return letter_grade

def main():
    number_grade = int(input("Input number grade: "))
    letter_grade = convert_grade_to_letter(number_grade)

    if letter_grade is not None:
        print("Letter grade: " + letter_grade)

main()

如何只在不使用循环的情况下验证整数并在输入不正确时退出？

2 个答案: