parameters had limitations, e.g. no string literals  C++20 relaxes these limitations  Allows floating-point types  Allows class types (but with some restrictions)  E.g. use-case: pass string literals Constants  <numbers>  Following mathematical constants are defined:  e, log2e, log10e  pi, inv_pi, inv_sqrtpi  ln2, ln10  sqrt2, sqrt3, inv_sqrt3  egamma  phi  In std::numbers78 std::source_location remove- erase-idiom83 Small Standard Library Additions  midpoint() to calculate the midpoint of two numbers  lerp() to do linear interpolation  New unsequenced_policy (execution::unseq): algorithm is allowed

C++203 Agenda  Compile-Time Rational Numbers  Durations  Clocks  Time Points  Dates  Time Zones 4 Agenda  Compile-Time Rational Numbers  Durations  Clocks  Time Points Rational Numbers  Defined in  Work with rational numbers at compile time  Always normalized representation  Needed for durations in the library6 Compile-Time Rational Numbers  Define intmax_t n { 1 }; intmax_t d { 60 }; using r1 = ratio; // Error7 Compile-Time Rational Numbers  Arithmetic with ratio_add, ratio_subtract, ratio_multiply, and ratio_divide: using r1 = ratio<1

@StephanTLavavej2 Getting Started • Please hold your questions until the end • Write down the slide numbers • Part 0: Overview • What's happened in the last year • Part 1: C++20 STL Features • Everything Torres and BillyONeal initially implemented this • GH-1048 by statementreply completed this • <numbers> Math Constants • GH-261 by SuperWig27 GitHub Development Part 228 How We Use GitHub • Code:

system scales greatly Aware of issues in 10 to 30 min per app Heavily testing on pull requests Numbers > 10 real test devices > 15 build machines (10 OS X, 4 Linux, 3 Windows) > 2000 tests > 600

them until after the session is over. • When asking questions, please reference slide numbers5 About Me: • Miya Natsuhara • Software Engineer on the Visual C++ Libraries Team (Microsoft)