Google's style guide about input/output parameters as pointers

Question

The Google C++ Style Guide draws a clear distinction (strictly followed by cpplint.py) between input parameters(→ const ref, value) and input-output or output parameters (→ non

Answer 1

They likely use it for consistency because they use output parameters both as references to existing memory (they're modifying previously initialized variables) and as actual outputs (the output arguments are assumed to be assigned by the function itself). For consistency, they use it as a way to more clearly indicate inputs vs. outputs.

If you never need a function/method to assign the memory of the output parameter, like returning a pointer from a lookup or allocating memory itself and returning it through a pointer, use references. If you need to do that but don't care about using pointers to act as an indication of whether a parameter is input or output, use references for output parameters when appropriate. There's no absolute requirement to use pointers in all cases unless the requirements of that function/method itself requires it.