Hi,
I did write a script to add 2 natural numbers, and send it to the mailing list of sed.
Because I found no list for sed developers, I send this script to this list. I did send it to
sed-users@yahoogroups.com, but that one is a private list, and cannot access it unless you subscribe the group.
It is not for sure the best place to send the script that adds 2 numbers :) , but probably one of you recomment me the good place where to send it.
The Hold space is used to add 2 digits . The Pattern Space is used to keep the numbers.
The general steps of the algorithm are the followings
* read both numbers in PS, and keep them separated by a space
* LOOP as time as there are still digits to add
* remove the last digit of every number, and move them to the end of PS
* append PS to HS
* commute to HS
* if there is only 1 digit, append a '0' (a number is longer than the other)
* transform every digit into points (N points for the digit N)
* if there are more than 10 points, transform the last 10 points to a SIGN ('+')
* convert the rest of N points into the digit N
* print the result:
* for a void result, print 0
* for a digit print and remove it
* for a '+', print 0, and convert '+' into a point
* for a digit and '+', print and remove the digit, and convert '+' into a point
* go back to Pattern Space
* remove the last processed digits
* END_LOOP
* if there is a point in HS, print a '1'
For a better display of the result, you can pipe the resulting stream via this:
sed ':a N ; s:\(.*\)\n\(.*\):\2\1:g ; ta;' # pipe the output via this
Example:
sed -f ./add.sed <<X | sed ':a N ; s:\(.*\)\n\(.*\):\2\1:g ; ta;'
10
101
X
111
I followed the principle kiss (keep it simple. stupid). The initial
zeros are displayed, as I did not want to complicate the code.
A colleague of mine found a bug (the void set,
id est the number 0 was not displayed sometimes).
If you find other errors, please report me.
Alin
add.sed