创建计算元音的函数时字符串索引超出范围问题

def count_vowels(string):
    vowels = ['a', 'e', 'i', 'o', 'u']
    count = 0
    for char in string:
        if char.lower() in vowels:
            count += 1
    return count

def calculate_vowels(string):
    try:
        return count_vowels(string)
    except IndexError:
        return "字符串索引超出范围"

# 示例用法
input_string = "Hello, World!"
result = calculate_vowels(input_string)
print("元音字母的数量：", result)