如何在同时包含数字的字符串中只使用大写字母？

def convert_to_uppercase(string):
    result = ""
    for char in string:
        if char.isdigit():
            uppercase_char = chr(int(char) + 65)
            result += uppercase_char
        else:
            result += char
    return result

# 示例输入字符串
input_string = "a1b2c3"
# 调用函数进行转换
output_string = convert_to_uppercase(input_string)
print(output_string)