trivial regex assistance - php

Question

I have a string as follows:
$str="1-3";
When I pass it through here:
preg_match('#(\\d+)\\s*-\\s*(\\d+)#', $str, $matches);
I get:
$matches[0] //1-3
$matches[1] //1
$matchers[2] //3
Now if you hass something like this:
$str="a-3";
You get
$matches //empty
This is correct since it is restricted to only integers.
Now my problem is i want to implement something that functions the same however for characters.
Here's what I have so far
preg_match('#(\\w+)\\s*-\\s*(\\w+)#', $str, $matches);
$str="a-d"
I get:
$matches[0] //a-d
$matches[1] //a
$matchers[2] //d
Which works great, however if u do this (notice the integer):
$str="a-5"
I get:
$matches[0] //a-5
$matches[1] //a
$matchers[2] //5
What i need is to enforce only alphabetic characters on the subsequent regex expression - thus if you pass a-5 it should be marked as errored.
Essentially i need the first regex solution applied to the second one with characters only

Answer 1

Simple Change the capturing group to ([a-zA-z]+), Like(DEMO):
([a-zA-Z]+)\s*-\s*([a-zA-Z]+)
\w, works by matching, any alphanumeric characters and _ underscore. If you only want to match alphabets then you need to provide the alphabets range like
a-z small letter and A-Z capital letters.

Answer 2

You could use unicode property \pL that means any letter in any language:
$arr = [
'a-d',
'1-5',
'1-d',
'ç-é',
];
foreach($arr as $str) {
if (preg_match('/(\pL)\s*-\s*(\pL)/u', $str, $matches)) {
print_r($matches);
} else {
echo "$str : error\n";
}
}
Output:
Array
(
[0] => a-d
[1] => a
[2] => d
)
1-5 : error
1-d : error
Array
(
[0] => ç-é
[1] => ç
[2] => é
)