411 REFERENCE · Wikibooks
C++ Language/Std/CRuntime/Time/TimespanAsCpuClockticks
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
The C-Runtime keeps track of the amount of time elapsed since the library started running within your program.
Query that value by calling std::clock().
Additional information about the clock() function (includes interactive examples)