C++核心準(zhǔn)則R.2: 只在接口中表示單獨(dú)對象使用原始指針?

R.2: In interfaces, use raw pointers to denote individual objects (only)

R.2: 只在接口中表示單獨(dú)對象使用原始指針

Reason(原因）

Arrays are best represented by a container type (e.g.,?vector?(owning)) or a?span?(non-owning). Such containers and views hold sufficient information to do range checking.

數(shù)組最好用容器類型（例如，vector(具有所有權(quán))）或者span(不包含所有權(quán))表示。容器或span包含可以用于范圍檢查的信息。

Example, bad(反面示例)

void f(int* p, int n)   // n is the number of elements in p[]
{
    // ...
    p[2] = 7;   // bad: subscript raw pointer
    // ...
}

The compiler does not read comments, and without reading other code you do not know whether?p?really points to?n?elements. Use a?span?instead.

編譯器不會讀注釋行，如果不看其他代碼你無法知道p實(shí)際上指向n個元素。使用span吧。

Example(示例)

void g(int* p, int fmt)   // print *p using format #fmt
{
    // ... uses *p and p[0] only ...
}

Exception(例外)

C-style strings are passed as single pointers to a zero-terminated sequence of characters. Use?zstring?rather than?char*?to indicate that you rely on that convention.

C風(fēng)格字符串作為指向以0結(jié)尾的字符序列的指針傳遞。使用zstring而不是char*以表明你遵守這個習(xí)慣。

Note(注意)

Many current uses of pointers to a single element could be references. However, where?nullptr?is a possible value, a reference may not be a reasonable alternative.

很多目前指向單獨(dú)要素的指針可以使用引用。然而，當(dāng)nullptr也是有效值時引用就不是一個合理的選擇。

Enforcement(實(shí)施建議)

• Flag pointer arithmetic (including?++) on a pointer that is not part of a container, view, or iterator. This rule would generate a huge number of false positives if applied to an older code base.

• 如果一個指針不是來自容器，view或者迭代器并存在指針運(yùn)算（包括++），進(jìn)行提示。這條準(zhǔn)則如果運(yùn)用于舊代碼會產(chǎn)生大量的假陽性結(jié)果（結(jié)果有問題但實(shí)際上沒有問題，譯者注）。
  

• Flag array names passed as simple pointers

• 提示用原始指針傳遞數(shù)組的情況。
  

原文鏈接：

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#r2-in-interfaces-use-raw-pointers-to-denote-individual-objects-only

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