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C# / .NET - replace first character in string (range operator ..)
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In this article, we would like to show you how to replace the first character in a string in C# / .NET.
Note: range operator
..was introduced in C# 8.0.
Quick solution:
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string text = "ABC";2
string replacement = "x";3
string result = replacement + text[1..];4
5
Console.WriteLine(result); // xBC
In this example, we will take the text string without the first character and add it at the end of the replacement.
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using System;2
3
public class StringUtils4
{5
public static void Main(string[] args)6
{7
string text = "ABC";8
string replacement = "x";9
string result = replacement + text[1..];10
11
Console.WriteLine(result); // xBC12
}13
}This approach is equivalent to the above one. Instead of + operator we concatenate the strings using string.Concat() method.
xxxxxxxxxx1
using System;2
3
public class StringUtils4
{5
public static void Main(string[] args)6
{7
string text = "ABC";8
string replacement = "x";9
string result = string.Concat(replacement, text[1..]);10
11
Console.WriteLine(result); // xBC12
}13
}In this example, we use Regex.Replace() with "^." regex to replace the first character in the text string.
Regex explanation:
^- matches the beginning of the string,.- matches any character except linebreaks.
xxxxxxxxxx1
using System;2
using System.Text.RegularExpressions;3
4
public class StringUtils5
{6
public static void Main(string[] args)7
{8
string text = "ABC";9
string replacement = "x";10
string pattern = @"^.";11
string result = Regex.Replace(text, pattern, replacement);12
13
Console.WriteLine(result); // xBC14
}15
}