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Use the replace() method to replace the first occurrence of a character in a string. The method takes a regular expression and a replacement string as parameters and returns a new string with one or more matches replaced. Copied!
sub() method will replace all pattern occurrences in the target string. By setting the count=1 inside a re. sub() we can replace only the first occurrence of a pattern in the target string with another string.
replace() The replace() method returns a new string with one, some, or all matches of a pattern replaced by a replacement . The pattern can be a string or a RegExp , and the replacement can be a string or a function called for each match. If pattern is a string, only the first occurrence will be replaced.
If we want to replace only the first occurrences of a substring in a string with another character or sub-string, then we need to pass the count argument as 1 in the replace() function, sample_str = "This is a sample string, where is need to be replaced."
I think you can use the overload of Regex.Replace to specify the maximum number of times to replace...
var regex = new Regex(Regex.Escape("o"));
var newText = regex.Replace("Hello World", "Foo", 1);
public string ReplaceFirst(string text, string search, string replace)
{
int pos = text.IndexOf(search);
if (pos < 0)
{
return text;
}
return text.Substring(0, pos) + replace + text.Substring(pos + search.Length);
}
here is an Extension Method that could also work as well per VoidKing request
public static class StringExtensionMethods
{
public static string ReplaceFirst(this string text, string search, string replace)
{
int pos = text.IndexOf(search);
if (pos < 0)
{
return text;
}
return text.Substring(0, pos) + replace + text.Substring(pos + search.Length);
}
}
There are a number of ways that you could do this, but the fastest might be to use IndexOf to find the index position of the letter you want to replace and then substring out the text before and after what you want to replace.
if (s.Contains("o"))
{
s = s.Remove(s.IndexOf('o')) + "Foo" + s.Substring(s.IndexOf('o') + 1);
}
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