How to replace a character within a matched pattern using ampersand (&)

Question

When we match a pattern using sed, the matched pattern is stored in the \"ampersand\" (&) variable. IS there a way to replace a character in this matched pattern using the a

Answer 1

you can first match a pattern and then change the text if matched:

echo "apple1" | sed '/apple/s/1/2/'    # gives you "apple2"

this code changes 1 to 2 in all lines containing apple