我想我已经解决了，试着看看这段代码：

def calc():

    again_or_not = input("Do you want to play [Y/N]: ")

    if again_or_not == "n":
        print("Good luck, see you soon")

    elif again_or_not == "y":
            # This program converts a numeric grade to an alpha grade

        input_bool = False

        while not input_bool:
            input_grade = int(input("Please enter the grade you wish to convert (0-100).\n"))
            if (input_grade >= 0 ) or (input_grade <= 100):
                input_bool = True

            output_grade = ""

            if input_grade >= 0 and input_grade <= 34:
                output_grade = "F"

            elif input_grade >= 35 and input_grade <= 39:
                output_grade = "MF"

            elif input_grade >= 40 and input_grade <= 49: 
                output_grade = "D"

            elif input_grade >= 50 and input_grade <= 59: 
                output_grade = "C"

            elif input_grade >= 60 and input_grade <= 69: 
                output_grade = "B"

            elif input_grade >= 70 and input_grade <= 79: 
                output_grade = "A-"
            
            elif input_grade >= 80 and input_grade <= 89: 
                output_grade = "A"
            
            elif input_grade >= 90 and input_grade <= 100:
                output_grade = "A+"

        print(f"{input_grade} = {output_grade}.")
        again_or_not2 = input("Do you want to try again [Y/N]: ")
        if again_or_not2 == "n":
            print("Good luck, see you soon")
        else:
            calc()

calc()

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代码

if (input_grade >= 0) or (input_grade <= 100):
    input_bool = True

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只检查一个条件是否为真，并传递到下一行。为了检查数字是否在0和100之间，您必须使用and运算符。
你也可以先检查if not input_bool:，然后再检查continue，以避免额外的条件检查，因为它甚至不在0-100之下。

试试这个：

input_bool = False

while not input_bool:
    input_grade = int(input("Please enter the grade you wish to         convert (0-100).\n"))
    if (input_grade >= 0) or (input_grade <= 100):
        input_bool = False

        output_grade = "Error"

    if 0 <= input_grade <= 34:
        output_grade = "F"

    elif 35 <= input_grade <= 39:
        output_grade = "MF"

    elif 40 <= input_grade <= 49:
        output_grade = "D"

    elif 50 <= input_grade <= 59:
        output_grade = "C"

    elif 60 <= input_grade <= 69:
        output_grade = "B"

    elif 70 <= input_grade <= 79:
        output_grade = "A-"

    elif 80 <= input_grade <= 89:
        output_grade = "A"

    elif 90 <= input_grade <= 100:
        output_grade = "A+"

    print(f"{input_grade} = {output_grade}.")

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问题出在你的if条件中。你正在使用or运算符，它将始终计算为True，因为任何等级输入都将是>= 0或<= 100。要解决这个问题，你应该使用and运算符来确保等级是>= 0和<= 100：

while not input_bool:
    input_grade = int(input("Please enter the grade you wish to convert (0-100).\n"))
    if (input_grade >= 0 ) and (input_grade <= 100):  # Alternatively if 0 <= input_grade <= 100:
        input_bool = True
    else:
        print("Invalid input. Please enter a grade between 0 and 100.")
        continue

    # Rest of your code

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此更改确保input_bool仅在等级在有效范围内时才设置为True。else块处理无效的输入情况，提示用户再次输入等级。