How to check if a string contains a substring in Bash

Question

I have a string in Bash:

string=\"My string\"

How can I test if it contains another string?

if [ $string ?? \'foo\' ]; then         


        

Answer 1

case $string in (*foo*)
  # Do stuff
esac

This is the same answer as https://stackoverflow.com/a/229585/11267590. But simple style and also POSIX Compliant.