Python-100-Days/07.字符串和常用数据结构--练习2：报错

UnboundLocalError: local variable 'code' referenced before assignment

增加code = ''后解决：

import random


def generate_code(code_len=4):
    """
    生成指定长度的验证码

    :param code_len: 验证码的长度(默认4个字符)

    :return: 由大小写英文字母和数字构成的随机验证码
    """
    
    code = ''
    all_chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
    last_pos = len(all_chars) - 1
    for _ in range(code_len):
        index = random.randint(0,last_pos)
        code += all_chars[index]
    return code


if __name__ == '__main__':
    print(generate_code(4))

Start by locating the exercise containing the generate_code function shown in the issue and run it to reproduce the UnboundLocalError. Confirm the exercise executes successfully and generates a code of the requested length without that error.