C++中如下的變數聲明見過嗎？ auto recommended = 200"000U;

01-06

void functionName() {
auto recommended = 200"000U;
auto min = 10"000U;

}
整型字面量中間可以加一個單個的單引號！有知道這個C++語法的說明說明，謝謝～

這段代碼在ScyllaDB代碼中看到，心中惶恐。因為我多年未曾見過一次；
這種寫法，以至於Source Insight無法真確的進行語法高亮。如圖：

C++14新語法

integer literal

單引號會被忽略，不要想太多。

C++14新特性，數字千位分割符，數學上雖然是逗號，不過C系語言逗號已經有其他用了，再用逗號歧義不好處理，就用單引號了。

順便說一下Source Insight這種老不更新的古董就拋棄了吧

C++ 14 : Digit separators
可以在數字字面量中任意插入

[N3781] Lawrence Crowl, Richard Smith, Jeff Snyder, Daveed Vandevoorde: Single-Quotation-Mark as a Digit Separator.

感謝評論指出，回去看了下，果然有問題。

An integer literal is a sequence of digits that has no period or exponent part. An integer literal may have a pre?x that speci?es its base and a su?x that speci?es its type. The lexically ?rst digit of the sequence of digits is the most signi?cant. A decimal integer literal (base ten) begins with a digit other than 0 and consists of a sequence of decimal digits. An octal integer literal (base eight) begins with the digit 0 and consists of a sequence of octal digits.22 A hexadecimal integer literal (base sixteen) begins with 0x or 0X and consists of a sequence of hexadecimal digits, which include the decimal digits and the letters a through f and A through F with decimal values ten through ?fteen. [Example: the number twelve can be written 12, 014, or 0XC. —end example]

來自N3337

An integer literal is a sequence of digits that has no period or exponent part, with optional separating single quotes that are ignored when determining its value.

來自N4140

所以這是C++14的新特性，可以在數字中任意位置添加。

===========原答案===========

我要是沒記錯的話是c++11的特性，用來分隔數字，每三位一個。