replace substring if follows number, eg screen resolution, php

Question

I have looked everywhere but I am stuck and need some help.
I believe I need a regex to replace a quote " (for inches) at the end of a number.
For example 21.5" with 21.5inch
I need to do it only if the " has a number before it. Thanks in advance!

Answer 1

The regex for this task is

(\d)"

Here is DEMO with explanation

Answer 2

Try this:

(?<=\d)"

https://regex101.com/r/lC9tZ7/2

It should grab the " as long as it follows a digit.

If it can have spaces between the digit and ", try this:

(?<=\d)\s*"

https://regex101.com/r/cT1bF7/3

Answer 3

Try (\d+\.{0,1}\d+)\s*"

Explanation: Lets try matching 21.54 inch

1. \d+ matches 21
2. \.{0,1} escapes decimal notation and matches if there's a . atleast 0 times (i.e., there is no decimal at all) and atmost 1 times (i.e., a number can only have at most 1 decimal). So, we have so far matched 21.
3. \d+ matches the remaining 54. So far matched 21.54
4. \s* forgives if there is any space followed by the number
5. " finally ensures that the number is followed by the inch notation.

Check this demo link here.