Why string.TrimEnd not removing only last character in string

Question

I have string as below

2,44,AAA,BBB,1,0,,,

So now i want to remove only last comma in above string. So i want output as

2,44,AAA,BBB,1,0,,

I decided to use TrimeEnd as below

str.ToString.TrimEnd(',')

But it removed all the commas after 0. So i get output as below

2,44,AAA,BBB,1,0

Why it removes all the 3 commas after 0? I just need to remove last character in string

Answer 1

Why it removes all the 3 commas after 0?

Because that's what it's documented to do:

Return value:
The string that remains after all occurrences of the characters in the trimChars parameter are removed from the end of the current string.

If you only want the final character removed, you could use:

if (str.EndsWith(","))
{
    str = str.Substring(0, str.Length - 1);
}

Or equivalently:

if (str.EndsWith(","))
{
    str = str.Remove(str.Length - 1);
}