How can I return all numeric values in PostgreSQL?

I had to select from the column all the values that contain numbers (NULL values aren’t interested). How can I make a query to my table using something like this:

SELECT c1
FROM t1 
WHERE c1 ...;

I tried to find suitable regular expressions, which are popular in many imperative programming languages, but they didn’t fit for PostgreSQL, unfortunately (or I used them incorrectly)

>Solution :

Possible solution:

SELECT c1 FROM t1 WHERE c1 ~ '^[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?$';