c# - Uppercase problems -

how can output when i'm using replace , toupper in visual studio c#

firstname

here's code:

private void button1_click(object sender, eventargs e) {     string input;     input = combobox1.text;     input = input.replace("_", "");     label1.text = input.first().tostring().toupper()                       + string.join("", input.skip(1));     } 

the output this:

firstname

if input "first_name" works:

var text = "first_name";  text = string.join("",     text         .split('_')         .where(x => !string.isnullorempty(x))         .select(x => new string(             x                 .take(1)                 .select(c => char.toupperinvariant(c))                 .concat(x.skip(1))                 .toarray())));