Syntactically, it almost was; and even this is no longer true today with C11 and later, More importantly, though - the syntax is not what matters. The language

Syntactically, it almost was; and even this is no longer true today with C11 and later, More importantly, though - the syntax is not what matters. The languages are very very different in idiomatic use. You just don't write programs the same way with C and with C++. And the gulf between the two only expands with time. A decent C program is almost certainly a poor C++ program, in terms of idioms, utilization of library facilities, and sometimes even in terms of performance (!).