How to remove character from string?

Question

I have a string which is getting from a userInput. What I want to do now is removing a unique character from this string but only remove it once. The main problem is that this unique character doesn't have a unique index. For example: User has input a string like : "0123456", and now I want to remove the first '1',so the string will be output like "023456". How ever, if a user input a string like "01123456", how can I remove the first '1' and make it looks like "0123456"? I am looking for a method that can be used for both of situation. I was using string.TrimStart(), but doesn't get what I want. How can I do this?

Answer 1

You could use Remove and IndexOf .

var str = "01123456";
var i = str.IndexOf('1'); // IndexOf returns -1 when there is no element found, so we need to handle that when calling remove.
var res = (i >= 0) ? str.Remove(i, 1) : str;
Console.WriteLine(res); // 0123456

Answer 2

I think you what you need is string.Remove method. See MSDN documentation here: https://docs.microsoft.com/en-us/dotnet/api/system.string.remove?view=netframework-4.7.2#System_String_Remove_System_Int32_System_Int32_

If you don't know where is your character, at first call string.IndexOf to find it. If this call returns nonnegaive number, call Remove to remove it. Just note that string is immutable so it will always create a new object.

Answer 3

yourstring = yourstring.IndexOf('1') != -1 ? yourstring.Remove(yourstring.IndexOf('1'), 1) : yourstring;

Answer 4

Another way would be to use a combination of Contains , Remove , and IndexOf :

if (userInput.Contains('1')) userInput = userInput.Remove(userInput.IndexOf('1'), 1);

Or if you want to be Linq-y...

userInput = string.Concat(userInput.TakeWhile(chr => chr != '1')
    .Concat(userInput.SkipWhile(chr => chr != '1').Skip(1)));