lpPreviousCount

lpPreviousCount is a variable name commonly seen in C and C++ code that follows historical Windows API naming conventions. The prefix lp indicates a long pointer, i.e., a pointer type, and PreviousCount describes the semantic meaning of the value being pointed to—the counter’s value prior to a modification. The name is descriptive in contexts where a function updates a counter and reports its previous value to the caller through a pointer parameter.

In typical usage, a function accepts a LONG* parameter named lpPreviousCount to return the value of a counter before it is updated. The function may perform the update atomically or with synchronization, and if the pointer is non-null, it writes the old value to the addressed location. This pattern lets callers obtain the prior state without requiring an additional read or separate return value.

lpPreviousCount often appears in code that implements synchronization primitives, counters, or other shared-state utilities where tracking the previous value is useful for decision logic or debugging. Many Windows API routines adopt similar pointer-parameter conventions, contributing to the recognizable lp prefix in legacy codebases.

Notes and caveats: the lp prefix is part of an older Hungarian-style naming convention and is not a guarantee of a specific type beyond indicating a pointer. Modern code may opt for clearer or more explicit names, such as prevCount or previousCount, and may prefer explicit pointer types or smart abstractions. When using such a parameter, programmers should validate that the pointer is non-null if the contract requires writing, and be mindful of thread-safety and memory visibility in concurrent contexts. See also Windows API naming conventions and interlocked or atomic operation patterns.