Online version of Why3, with micro-C input format
This version of Why3 is intended for teaching purposes.
Its input format is a tiny subset of C, called "micro-C",
and described here.
Note: the command-line version of Why3 is also supporting this
input format, for files with suffix .c.
Verifying a program
Click on the gears button to launch the verification.
Verification conditions (VCs) then appear in the right panel, in
the Task List tab, and
Alt-Ergo is run on each of them with a default time limit (that
can be set in the Settings menu).
When a VC is not proved, there are several options:
- use the contextual menu to rerun Alt-Ergo with a larger
time limit (e.g. 1000 or 5000 steps instead of 100);
- use the contextual menu to split the VC and rerun Alt-Ergo
on each sub-VC (split and prove);
- use the Task View tab to investigate the problematic VC,
for wrong or missing elements of specification (precondition,
postcondition, invariant);
- add intermediate assertions in the code, using //@
assert ...;.