Introduction to isalpha () method

Introduce

str.isalpha() The implementation is to return if the string has at least one character and all characters are letters True, Otherwise return to False.

application ：

for example ACM There is a sorting problem in the algorithm ：
Write a program , Sort the characters in the input string as follows .
The rules 1 ： The English letters come from A To Z array , Case insensitive .
Such as , Input ： Type Output ： epTy
The rules 2 ： When the case of the same English letter exists at the same time , Sort according to the input order .
Such as , Input ： BabA Output ： aABb
The rules 3 ： Other characters other than English letters remain in their original position .
Such as , Input ： By?e Output ： Be?y
Data range ： The length of the input string meets the requirements 1 \le n \le 1000 \1≤n≤1000

Input description ：
Input string
Output description ：
Output string

Input ：A Famous Saying: Much Ado About Nothing (2012/8).
Output ：A aaAAbc dFgghh: iimM nNn oooos Sttuuuy (2012/8)

Code ：

while True:
    try:
        s = input()
        a = ''
        for i in s:
            if i.isalpha(): #  Make letter type judgment 
                a += i
        b = sorted(a, key=str.upper)  #  According to capitalization ASC Sort code 
        index = 0
        d = ''
        for i in range(len(s)):
            if s[i].isalpha():
                d += b[index]
                index += 1
            else:
                d += s[i]
        print(d)
    except:
        break