单引号作为大量分隔符？

Question

我一直在尝试编译 MAME 项目中的部分代码，但我运行在 attotime.h 中编译此部分时遇到了问题：

// core components of the attotime structure
typedef s64 attoseconds_t;
typedef s32 seconds_t;

// core definitions
constexpr attoseconds_t ATTOSECONDS_PER_SECOND_SQRT = 1'000'000'000;
constexpr attoseconds_t ATTOSECONDS_PER_SECOND = ATTOSECONDS_PER_SECOND_SQRT * ATTOSECONDS_PER_SECOND_SQRT;
constexpr attoseconds_t ATTOSECONDS_PER_MILLISECOND = ATTOSECONDS_PER_SECOND / 1'000;
constexpr attoseconds_t ATTOSECONDS_PER_MICROSECOND = ATTOSECONDS_PER_SECOND / 1'000'000;
constexpr attoseconds_t ATTOSECONDS_PER_NANOSECOND = ATTOSECONDS_PER_SECOND / 1'000'000'000;

constexpr seconds_t ATTOTIME_MAX_SECONDS = 1'000'000'000;

给出错误：

In file included from ~/git/mame/src/emu/emu.h:32,
                 from main.cpp:1:
~/git/mame/src/emu/attotime.h:54:56: warning: multi-character character constant [-Wmultichar]
 constexpr attoseconds_t ATTOSECONDS_PER_SECOND_SQRT = 1'000'000'000;
                                                        ^~~~~
~/git/mame/src/emu/attotime.h:54:64: warning: missing terminating ' character
 constexpr attoseconds_t ATTOSECONDS_PER_SECOND_SQRT = 1'000'000'000;
                                                                ^
~/git/mame/src/emu/attotime.h:54:64: error: missing terminating ' character
 constexpr attoseconds_t ATTOSECONDS_PER_SECOND_SQRT = 1'000'000'000;
                                                                ^~~~~
compilation terminated due to -Wfatal-errors.
make: *** [<builtin>: main.o] Error 1

我没有修改代码或包含，但我正在编译我自己的 Makefile。我从未见过这种语法，也无法在网上找到任何相关信息。

是否有启用此功能的 g++ 标志？我知道我可以使用 -Wno-multichar 来摆脱警告，但仍然存在 missing terminating ' character 错误。

Answer 1

使用 -std=c++14，因为分隔符是 C++14 的一项功能。参见：https://en.cppreference.com/w/cpp/language/integer_literal

Optional single quotes(') may be inserted between the digits as a separator. They are ignored by the compiler. [since C++14]

单引号作为大量分隔符？

Single quotes as separator in large number?

c++

syntax

emulation