带单引号的整数文字？

Question

赋值的究竟是什么？我很惊讶这已经编译好了。

//g++  7.4.0

#include <iostream>

int main()
{
    auto value = 123'456'7;
    std::cout << value << std::endl;

    value += 1;
    std::cout << value << std::endl;
}

输出：

1234567
1234568

Answer 1

C++ 允许单引号分隔数字以便于阅读：

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.

Answer 2

自 C++14 起，

来自 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.

带单引号的整数文字？

Integer literal with single quotes?

c++

integer

literals