String.Replace ignoring case

Question

I have a string called \"hello world\"

I need to replace the word \"world\" to \"csharp\"

for this I use:

string.Replace(\"World\", \"csharp\         


        

Answer 1

Lots of suggestions using Regex. How about this extension method without it:

public static string Replace(this string str, string old, string @new, StringComparison comparison)
{
    @new = @new ?? "";
    if (string.IsNullOrEmpty(str) || string.IsNullOrEmpty(old) || old.Equals(@new, comparison))
        return str;
    int foundAt = 0;
    while ((foundAt = str.IndexOf(old, foundAt, comparison)) != -1)
    {
        str = str.Remove(foundAt, old.Length).Insert(foundAt, @new);
        foundAt += @new.Length;
    }
    return str;
}

Answer 2

Using @Georgy Batalov solution I had a problem when using the following example

string original = "blah,DC=bleh,DC=blih,DC=bloh,DC=com"; string replaced = original.ReplaceIgnoreCase(",DC=", ".")

Below is how I rewrote his extension

public static string ReplaceIgnoreCase(this string source, string oldVale, 
string newVale)
    {
        if (source.IsNullOrEmpty() || oldVale.IsNullOrEmpty())
            return source;

        var stringBuilder = new StringBuilder();
        string result = source;

        int index = result.IndexOf(oldVale, StringComparison.InvariantCultureIgnoreCase);
        bool initialRun = true;

        while (index >= 0)
        {
            string substr = result.Substring(0, index);
            substr = substr + newVale;
            result = result.Remove(0, index);
            result = result.Remove(0, oldVale.Length);

            stringBuilder.Append(substr);

            index = result.IndexOf(oldVale, StringComparison.InvariantCultureIgnoreCase);
        }

        if (result.Length > 0)
        {
            stringBuilder.Append(result);
        }

        return stringBuilder.ToString();
    }

Answer 3

You can also try the Regex class.

var regex = new Regex( "camel", RegexOptions.IgnoreCase ); var newSentence = regex.Replace( sentence, "horse" );

Answer 4

.Net Core has this method built-in: Replace(String, String, StringComparison) Doc. Now we can simply write: "...".Replace("oldValue", "newValue", StringComparison.OrdinalIgnoreCase)

Answer 5

(Edited: wasn't aware of the `naked link' problem, sorry about that)

Taken from here:

string myString = "find Me and replace ME";
string strReplace = "me";
myString = Regex.Replace(myString, "me", strReplace, RegexOptions.IgnoreCase);

Seems you are not the first to complain of the lack of case insensitive string.Replace.