how to implement loop using flow

i would like to ask,how to implement loop using flow?
for example i would like to generate output:
in debug log from input string abcd

i don’t know how many times it will gonna be depends on the total char on input

Normally one doesn’t manipulate strings at the character level in FLOW. That’s typically too low of a level. If you need to manipulate a string at this level you’re probably better off creating a Java service.

Comparing features of two languages and applying the techniques that you know in one language (e.g. Java) to another (e.g. FLOW) can be very helpful in learning the new language. However, don’t make the mistake of coding FLOW services in the same manner that you would code Java.

I agree with Rob. You’d probably not be using Flow for this type of logic. However, if you must see how you could implement the logic above in Flow, take a look at the attached sample.