编辑要求输入用户名的程序。它应该检查前四个字符是否为字母，第五和第六个字符是否为数字。用PYTHON

in user：将遍历每个用户字符，并每次将其分配给。 删除你的第二个。这应该行得通。

您可以直接在字符串数据类型中使用索引方法，如

user = input("Enter your username (It should be of minimum 7 characters): ")
for a in user:
    for a in range(0,4):
        if (a.isalpha()) == True:
            print("The first four character are alphabet !")
        else:
            print("the first four characters are not alphabets !")
            break
for a in user:
    for a in range(4,6):
        if a.isdigit()==True:
            print("The fifth and sixth characters are digits !")
        else:
            print("The fifth and sixth characters are not digits !")
            break

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检查数字也一样。您也可以尝试循环来迭代索引。

请解释问题。当前代码有问题吗？这里没有问题。你的帖子里有什么你不明白的吗？

if user[0].isalpha() == True and user[1].isalpha() == True and user[2].isalpha() == True  and user[3].isalpha() == True :
    print("The first four character are alphabet !")
else:
    print("the first four characters are not alphabets !")