Editing Sequence point (section)

=== C++17 ===

C++17 restricted several aspects of evaluation order. The {{code|new}} expression will always perform the memory allocation before evaluating the constructor arguments. The operators {{code|<<}}, {{code|>>}}, {{code|.}}, {{code|.*}}, {{code|->*}}, and the subscript and function call operator are guaranteed to be evaluated left to right (whether they are overloaded or not). For example, the code

<syntaxhighlight lang="cpp">
std::cout << a() << b() << c();   // parsed as (((std::cout << a()) << b()) << c());
</syntaxhighlight>

is newly guaranteed to call {{code|a}}, {{code|b}} and {{code|c}} in that order. The right-hand side of any assignment-like operator is evaluated before the left-hand side, so that <code>b() *= a();</code> is guaranteed to evaluate {{code|a}} first. Finally, although the order in which function parameters are evaluated remains implementation-defined, the compiler is no longer allowed to interleave ''sub-expressions'' across multiple parameters.<ref>{{cite web |last1=Dos Reis |first1=Gabriel |last2=Sutter |first2=Herb |last3=Caves |first3=Jonathan |title=Refining Expression Evaluation Order for Idiomatic C++ |url=https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0145r3.pdf |website=open-std.org |access-date=28 April 2023 |pages=1–5 |date=2016-06-23}}</ref>