Question

I am having two string builders in which one holds the complete data and the other holds the data that should be replaced but I am unable to replace the content.

This is the code i have written

StringBuilder sb1 = new StringBuilder();
StringBuilder sb2 = new StringBuilder();

sb1.AppendLine("1111111111");
sb1.AppendLine("555555555");
sb1.AppendLine("666666660");
sb1.AppendLine("6666666601");
sb1.AppendLine("6666666602");
sb1.AppendLine("6666666603");
sb1.AppendLine("888888888");
sb1.AppendLine("99999999");
sb1.AppendLine("555555555");
sb1.AppendLine("666666661");
sb1.AppendLine("666666662");
sb1.AppendLine("666666663");
sb1.AppendLine("666666664");
sb1.AppendLine("888888888");
sb1.AppendLine("99999999");

sb2.AppendLine("6666666601");
sb2.AppendLine("666666661");

sb1 = sb1.Replace(sb2.ToString().TrimEnd(charRemove), "");
sb1 = sb1.Replace(sb2.ToString(), ""); // this also i tried

I would like to remove sb2 content

Answer 1

You mustn’t use StringBuilder for sb2.

To make it short, you are telling .NET to replace 6666666601666666661 in sb1.

Try:

List<string> list2 = new List<string>();
list2.Append("6666666601")
list2.Append("666666661")

foreach (var str in list2)
{
    sb1.Replace(str + "\r\n", ""); // the \r\n are because you used `AppendLine`
}

(and I’m not even sure you want to use a StringBuilder for sb1. StringBuilder is used to “compose” strings, not to “collect” them)

Note that this is still wrong wrong wrong!

You would be much better to begin the sb1 with an empty line, like this:

sb1.AppendLine("");

so that you can Replace like this:

sb1.Replace("\r\n" + str + "\r\n", "\r\n"); // the \r\n are because you used `AppendLine`

in this way, 99 won’t mach 1999, because 1999 will be \r\n1999\r\n while 99 will be \r\n99\r\n (we are adding a blank line at the beginning of the StringBuilder so that even the first element is preceeded by a \r\n. We are replaceing with \r\n because we are matching TWO \r\n, one before and one later, but one of the two must be preserved.)

I’ll add that perhaps you simply exchanged StringBuilder for a collection of strings, and perhaps you wanted to do this:

List<string> str1 = new List<string>();
str1.Add("555555555");
str1.Add("666666660");
str1.Add("6666666601");
str1.Add("666666661");

List<string> str2 = new List<string>();
str2.Add("6666666601");
str2.Add("666666661");

str1.RemoveAll(p => str2.Contains(p));