[PHP]: Verificar se a string tem caracteres inválidos.

/*
                @Função: Verificar se a string tem caracteres inválidos.
                @Créditos: [iPs]SuYaNw
*/

function IsValidString($str)
{
    if(strstr($str, "'") || strstr($str, "!") ||  strstr($str, "@") ||  strstr($str, "#") ||
    strstr($str, "$") ||  strstr($str, "%") ||  strstr($str, "¨") ||  strstr($str, "&") ||
    strstr($str, "*") ||  strstr($str, "(") ||  strstr($str, ")") ||  strstr($str, "-") ||
    strstr($str, "_") ||  strstr($str, "+") ||  strstr($str, "+") ||  strstr($str, "¹") ||
    strstr($str, "²") ||  strstr($str, "³") ||  strstr($str, "ª") || strstr($str, "{") ||
    strstr($str, "[") ||  strstr($str, "]") ||  strstr($str, "}") ||  strstr($str, "º") ||
    strstr($str, "´") ||  strstr($str, "`") ||  strstr($str, "^") ||  strstr($str, "~") ||
    strstr($str, "<") ||  strstr($str, ",") ||  strstr($str, ".") ||  strstr($str, ">") ||
    strstr($str, ":") ||  strstr($str, ";") ||  strstr($str, "/") ||  strstr($str, "°") ||
    strstr($str, "?") ||  strstr($str, "|") || is_numeric($str))
    {
        return false;
    }
    return true;
}