Logical operators issue - php

Question

Given the below variables:
$field1;
$field2;
$field3;
$field4;
$field5;
How can I use logical operators so that the user has to fill in either field: 1,2,3 OR either field 1, 2, 4, 5. If user does not do one of the following, then I want to give error required fields not complete.
I have tried:
if ((!$field1 | !$field2 |!$field3) | (!$field1 | !$field2 |!$field4|!$field5))
$errors[] = 'You did not complete all of the required fields.';

Answer 1

if (!
// Exactly 1,2,3 are filled in (not 4, 5)
(!empty($field1) && !empty($field2) && !empty($field3) && empty($field4) && empty($field5))
// or Exactly 1,2,4,5 are filled in (not 3)
&& !(!empty($field1) && !empty($field2) && !empty($field4) && !empty($field5) && empty($field3))
) {
// print error
}

Answer 2

Let a = not empty $field1, b = not empty $field2, ..., e = not empty $field5
You want
(a && b && c) || (a && b && d && e)
= (a && b) && ( c || (d && e))
In php:
if(!empty($field1) && !empty($field2) &&
( !empty($field3) || (!empty($field4) && !empty($field5))
) {
// process
} else {
// error
}
If you consider 0 as a valid value use isset in place of empty.
Finally get to use those algebra I learned in school.

Answer 3

Try:
if (!empty($field1) && !empty($field2) && !empty($field3)) {
//process
} else if (!empty($field1) && !empty($field2) && !empty($field4) && !empty($field5)) {
//process
} else {
$errors[] = 'You did not complete all of the required fields.';
}
Or, require that no extra fields are filled in for a given option:
if (!empty($field1) && !empty($field2) && !empty($field3) &&
empty($field4) && empty($field5)) {
//process
} else if (!empty($field1) && !empty($field2) && !empty($field4) && !empty($field5) &&
empty($field3)) {
//process
} else {
$errors[] = 'You did not complete all of the required fields.';
}

Answer 4

I am sure where the $fields are comming from, but the following might do the trick:
if (!(isset($field1) && isset($field2) && isset($field3)) || !(isset($field1) && isset($field2) && isset($field3) && isset($field4)){
//Set the error
}

Answer 5

I occasionally do something like the following for simple validations such as this
$fields = array('field1', 'field2', 'field3', 'field4', 'field5');
foreach($fields as $field) {
if(!isset($_POST[$field]) || strlen(trim($_POST[$field])) == 0) {
// set error message
}
}