Validate characters only with letters and spaces (including accents)

Question

How can I validate a string and accept only letters with or without accent and spaces? I read a little about the ctype_alpha, but it didn’t work with accented lyrics, although I set the configs to pt_br:

setlocale(LC_ALL, 'pt_BR', 'pt_BR.UTF-8', 'pt_BR.UTF-8', 'portuguese');

Answer 1

The function ctype_alpha only checks if the characters are in the range A-Za-z. One option is to use preg_match with the expression [\pL\s]+ to correspond only to letters and spaces.

function validar($string) {
    return !!preg_match('|^[\pL\s]+$|u', $string);
}

var_dump(validar("joÃO Maria")); // true
var_dump(validar("joao12"));     // false
var_dump(validar("Joao"));       // true
var_dump(validar("J0ao"));       // false
var_dump(validar(" "));          // true

_{The !! before the preg_match is used to return the boolean result.}

The modifier u in regular expression is to treat the string like UTF-8.