How to send a simple string between two programs using pipes?

Question

I tried searching on the net, but there are hardly any resources. A small example would suffice.

EDIT I mean, two different C programs communicating with each other.

Answer 1

What one program writes to stdout can be read by another via stdin. So simply, using c, write prog1 to print something using printf() and prog2 to read something using scanf(). Then just run

./prog1 | ./prog2