It is not easy to change char value or update or remove in string when we use a c# language

It’s good with Stringbuilder for that

https://school.programmers.co.kr/learn/courses/30/lessons/12951

While I was solving the problem below from programmars, there are requirement to change to capital charcter Firstly I tried to change with normal c sharp string api but not was easy

I got a hint from goole, realized string builder advantages.

it’s easy to change char in string. let ‘s use string builder and see the offical doc

https://learn.microsoft.com/ko-kr/dotnet/standard/base-types/stringbuilder