A two-stroke, or two-cycle, engine is a type of internal combustion engine which completes a power cycle with two strokes (up and down movements) of the piston during only one crankshaft revolution. This is in contrast to a  four-stroke engine , which requires four strokes of the piston to complete a power cycle. two-stroke engine, in this case with an expansion chamber illustrates the effect of a reflected pressure wave on the fuel charge. This is essential for maximum charge pressure (volumetric efficiency) and fuel efficiency. It is used on most high-performance engine designs.
More than that, because the array is a reference type, the amount of memory that resides on the stack along with the containing struct for a particular array is always equivalent to the native int pointer size (which is 32 on 32 bit Windows and 64 on 64 bit windows).
Underlying every R object is a C structure (or struct) that describes how that object is stored in memory. The struct includes the contents of the object, the information needed for memory management, and, most importantly for this section, a type. This is the base type of an R object.