Regex diacritics in C# not filtering on IsMatch -

i want return bool check string contains letters, numbers spaces , dashes. letters can foreign alphabets , need accept letters such é, à, î, or ô. line of code have:

if (regex.ismatch(this.userfirstname, @"^[a-za-z0-9À-ž_ -]") == false) { return false; } 

however, returns true if have #@! in string; here on image switched ^ see if makes difference doesn't.

what need change expected result: if there characters such #, @, or ! in string return false.

the main issue regex checks first character because of ^ anchor (start of string) , no quantifiers character class defined (i.e. 1 occurrence tested). thus, sylvain#@! pass starts allowed character.

you need use \p{l} shorthand class unicode letters both ^ , $ anchors , + quantifier:

if (regex.ismatch(this.userfirstname, @"^[\p{l}\p{n}\p{zs}_-]+$") == false) {   return false;  } 

see regexstorm demo

in regex, replaced 0-9 shorthand class \p{n} (unicode class numeric characters), , \p{zs} (unicode spaces). see more details @ msdn supported unicode general categories. if plan allow "regular" digits , regular space, keep 0-9 range , in regex:

@"^[\p{l}0-9 _-]+$"