$ symbol in c++
c++, locking, multithreading, syntax
Solution
It is being used as part of an identifer.
`[C++11: 2.11/1]` defines an identifier as "an arbitrarily long sequence of letters and digits." It defines "letters and digits" in a grammar given immediately above, which names only numeric digits, lower- and upper-case roman letters, and the underscore character explicitly, but does also allow "other implementation-defined characters", of which this is presumably one.
In this scenario the `$` has no special meaning other than as part of an identifier — in this case, the name of a variable. There is no special significance with it being at the start of the variable name.
Problem
I read the following code from an open source library. What confuses me is the usage of dollar sign. Can anyone please clarify the meaning of $ in the code. Your help is greatly appreciated! ``` __forceinline MutexActive( void ) : $lock(LOCK_IS_FREE) {} void lock ( void ); __forceinline void unlock( void ) { __memory_barrier(); // compiler must not schedule loads and stores around this point $lock = LOCK_IS_FREE; } protected: enum ${ LOCK_IS_FREE = 0, LOCK_IS_TAKEN = 1 }; Atomic $lock; ```