PHP Form Validation - Deprecated Function eregi() - php

Question

I've just raised a separate question on a problem with an enquiry form that had a deprecated eregi PHP function. Unfortunately, there's another file I missed that validates the form which is riddled with them :(
Here's the code below:
/* ERRORS */
function error($str) // private
{
$this->error = true;
$this->error_string .= $str;
}
/* VALIDATE FIELD AGAINST TYPE */
function checkit($value, $type) // private
{
$length = "";
if (eregi("^MIN[0-9]+$", $type)) {
$tmp = explode(":", $type);
$length = $tmp[1];
$type = "MINLENGTH";
}
if (eregi("^MAX[0-9]+$", $type)) {
$tmp = explode(":", $type);
$length = $tmp[1];
$type = "MAXLENGTH";
}
switch ($type) {
case "NOT_EMPTY":
$this->error_tmp = "string cannot be empty";
return $this->not_empty($value);
break;
case "MINLENGTH":
if (strlen($value) < $length) {
$this->error_tmp = "string to short";
return false;
} else {
return true;
}
break;
case "MAXLENGTH":
if (strlen($value) > $length) {
$this->error_tmp = "string to long";
return false;
} else {
return true;
}
break;
case "ALPHA":
$exp = "^[a-z]+$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not alpha";
return false;
}
break;
case "ALPHASPACE":
$exp = "^[a-z ]+$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not alphaspace";
return false;
}
break;
case "ALPHANUM":
$exp = "^[a-z0-9]+$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not alphanum";
return false;
}
break;
case "ALPHANUMSPACE":
$exp = "^[a-z0-9 ]+$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not alphanumspace";
return false;
}
break;
case "NUMERIC":
$exp = "^[0-9]+$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not numeric";
return false;
}
break;
case "NUMERICPLUS":
$exp = "^[0-9+-.]+$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not numericplus";
return false;
}
break;
case "EMAIL":
$exp = "^[A-Z0-9._%-]+#[A-Z0-9.-]+\.[A-Z]{2,4}$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "not a valid email";
return false;
}
break;
case "YYYYMMDD":
$exp = "^(19|20)[0-9][0-9][- /.](0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not YYYYMMDD";
return false;
}
break;
case "DDMMYYYY":
$exp = "^(0[1-9]|[12][0-9]|3[01])[- /.](0[1-9]|1[012])[- /.](19|20)[0-9][0-9]$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not DDMMYYYY";
return false;
}
break;
case "MMDDYYYY":
$exp = "^(0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])[- /.](19|20)[0-9][0-9]$";
if ($this->not_empty($value) && eregi($exp, $value)) {
return true;
} else {
$this->error_tmp = "string not MMDDYYYY";
return false;
}
break;
default:
if ($this->not_empty($value) && $this->regex($type, $value)) {
return true;
} else {
$this->error_tmp = "string not valid";
return false;
}
}
}
/* NOT_EMPTY */
function not_empty($value) // private
{
if (trim($value) == "") {
return false;
} else {
return true;
}
}
/* REGULAR EXPRESSION */
function regex($regex, $value) // private
{
$the_regex = 'ereg("' . $regex . '", "' . $value . '")';
$the_code = '<?php if(' . $the_regex . ') { return true; } else { return false; } ?>';
if (!eval('?>' . $the_code . '<?php ')) {
return false;
} else {
return true;
}
}
}
Are there too many to change?
I hope someone can help?
Thanks in advance, kind regards
Brian

Answer 1

Regex has the "case-insensitive" way to match a string. If you put the letter "i" at the end of the regular expression, the function preg_match() will match the string even if you are searching a lowercase sentence in an uppercase string.
In the case ALPHA, you can use this regular expression:
$exp = "/^[a-z]+$/i";
instead of
$exp = "^[a-z]+$";
Using this, you can change the PHP functions from eregi($exp, $value) to preg_match($exp, $value), which will return TRUE if there are matches.
You can read the related documentation of preg_match() function here: https://www.php.net/manual/en/function.preg-match.php
Andrea