php regular expression not matching correctly

Question

This is a simplified example, but when I run this code the first does not match as it should. It only matches the first part and nothing else. The other two occurrences match properly so I have no idea why the first wouldn't.

$str = 'What is 5 plus three?What is 4 plus three?What is 4 plus two?';

$replacees = [
'/What is (.*?) plus two\?/',
'/What is (.*?) plus three\?/',
];
$replacers = [
'I know $1 and 2.',
'I know $1 and 3.',
];

print_r( preg_replace($replacees, $replacers, $str) );

The results from that are:

I know 5 plus three?I know 4 and 3.What is 4 and 2.

But I'm expecting:

I know 5 and 3.I know 4 and 3.I know 4 and 2.

Answer 1

Hi All what you did was correct just flip the code as I have shown here.

<?
 $str = 'What is 5 plus three?What is 4 plus three?What is 4 plus two?';

$replacees = [
'/What is (.*?) plus three\?/',
'/What is (.*?) plus two\?/',

];
$replacers = [
 'I know $1 and 3.',
 'I know $1 and 2.',

];

print_r( preg_replace($replacees, $replacers, $str) );

I just flipped off the code and this is working now.

Answer 2

You should make global searching and as i see you changed last number word, so the code is:

/(?:What is ([\d])* plus (?:[\w]+)\?)/g

Of course you can make array of one, two, etc and replace it. Example:

$arrayN = array('one'=>1, 'two'=>2, 'three'=>'3');

Then change the expression like:

/(?:What is ([\d])* plus ([\w]+)\?)/g

and add to replace string:

I know $1 and $2 .

All word numbers change to numbers.