Mostly, of course, C is Thompsonized BCPL (that is, B) with types.
You don't have to look too hard to find PL/1 and Fortran, either.
A central principle in programming language design is don't look at previous
work and avoid the landmines.
A case in C was =+ =* =- and so forth. If the Revised A68 report chapter 9
had been studied with care, the ambiguity would have been immediately noticed.
A case in Ada had to do with what every they call structure display. The long
form is type-name(member1,...,membern) and short form is (member1,...,membern).
If the short form only has one member, (member), it is ambiguous with a
parenthised expression. Again the A68 directly dealt with this problem by
requiring a collateral clause to have zero or more than one unit.
One of the nicest things about the Revised Report was a complete and formal
definition. It might take a bit work, but every question could be resolved.
Why bother? Isn't much more fun to let each compiler have its own
interpretation? comp.lang.c and comp.lang.ada consume a large bandwidth as
people try to decide what is and is not legal and what it means.
(I take it back--I have been informed C does have a formal definition:
"Whatever PCC does on a VAX.")