用另一个替换字符串的第一部分

Question

I need to replace multiple file names in a folder. Here is one of the files:

Abc.CDE.EFG

I need to replace the first part of the string before the dot ("ABC") and replace it with: "zef".

Any ideas? I found this but it takes out the dot and not sure how to add the "zef".

var input = _FileInfo.ToString(); 
var output = input.Substring(input.IndexOf(".").Trim())

Answer 1

Since the question is tagged with regex, you can use a regular expression like so:

var input = "abc.def.efg";
var pattern = "^[^\\.]+";
var replacement = "zef";
var rgx = new Regex(pattern);
var output = rgx.Replace(input, replacement);

Source: https://msdn.microsoft.com/en-us/library/xwewhkd1(v=vs.110).aspx

Answer 2

You are almost there, try:

string myString = "Abc.CDE.EFG";    

//This splits your string into an array with 3 items
//"Abc", "CDE" and "EFG"    
var stringArray = myString.Split('.');  

//Now modify the first item by changing it to "zef" 
stringArray[0] = "zef"; 

//Then we rebuild the string by joining the array together
//delimiting each group by a period
string newString = string.Join(".", stringArray);

With this solution you can independently access any of the "blocks" just by referencing the array by index.

Fiddle here

Answer 3

Try this:

    var input = _FileInfo.ToString(); 
    var output = "zef" + input.Substring(input.IndexOf("."));

Answer 4

If you know the length of the first string , you can replace mentioning number of characters starting from position until the length you want to replace else.

string s = "Abc.CDE.EFG";
                string [] n = s.Split('.');
                n[0] = "ZEF";
                string p = string.Join(".",n);
                Console.WriteLine(p);
            }