C# how to pick out certain part in a string

Question

I have a string in a masked TextBox that looks like this:

123.456.789.abc.def.ghi

"---.---.---.---.---.---"  (masked TextBox format when empty, cannot use underscore X(  )

Please ignore the value of the characters (they can be duplicated, and not unique as above). How can I pick out part of the string, say "789"? String.Remove() does not work, as it removes everything after the index.

Answer 1

Do you mean you want to obtain that part of the string? If so, you could use string.Split

string s = "123.456.789.abc.def.ghi";
var splitString = s.Split('.');
// splitString[2] will return "789"

Answer 2

You could simply use String.Split (if the string is actually what you have shown)

string str = "123.456.789.abc.def.ghi";
string[] parts = str.Split('.');
string third = parts.ElementAtOrDefault(2); // zero based index
if(third != null)
    Console.Write(third);

I've just used Enumerable.ElementAtOrDefault because it returns null instead of an exception if there's no such index in the collection(It falls back to parts[2] ).

Answer 3

You could use Split in order to separate your values if the . is always contained in your string.

string input = "123.456.789.abc.def";

string[] mySplitString = input.Split('.');

for (int i = 0; i < mySplitString.Length; i++)
{
    // Do you search part here
}

Answer 4

尝试使用Replace 。

String.Replace("789", "")

Answer 5

Finding a string:

string str="123.456.789.abc.def.ghi";
int i = str.IndexOf("789");
string subStr = str.Substring(i,3);

Replacing the substring:

  str = str.Replace("789","").Replace("..",".");

Regex:

  str = Regex.Replace(str,"789","");

The regex can give you a lot of flexibility finding things with minimum code, the drawback is it may be difficult to write them

Answer 6

If you know the index of where your substring begins and the length that it will be, you can use String.Substring() . This will give you the substring:

String myString = "123.456.789";
// looking for "789", which starts at index 8 and is length 3
String smallString = myString.Substring(8, 3);

If you are trying to remove a specific part of the string, use String.Replace() :

String myString = "123.456.789";
String smallString = myString.Replace("789", "");

Answer 7

var newstr = new String（str.where（c =>“ 789”））。tostring（）; ..我想这会起作用，或者您可以像这样使用sumthng