Replace string before dot with another string

Question

I am having a string like below :

String str = "abc.History_logs";

Now I want to replace string before dot with this fixed string : apc

So final string will be like this :

apc.History_logs;

Code :

String str = "abc.History_logs";
string final = string.Join('apc.',str.Substring(str.IndexOf(".") + 1).Trim()); //error:invalid arguments for join

Answer 1

You can simply use string.Concat

string final = string.Concat("apc.", str.Substring(str.IndexOf(".") + 1).Trim());

I don't think there is an overloaded method exists for String.Join(String, String)

Answer 2

您可以使用此正则表达式

Regex.Replace(str,@".*?\.","apc.")

Answer 3

此Regex模式将忽略点本身，从而使您可以替换所需的任何内容而不必记住重新插入点：

Regex.Replace(str, @".*?(?=\.)", "apc");

Answer 4

string.Replace method looks more suitable for this

    string source = "abc.d";
    string target = "apc";
    source = source.Replace(source.Split('.')[0], target);