問題描述
我有一個(gè) ObjectArray
typedef map<int64_t, std::unique_ptr<Class1>> ObjectArray;
為 Class1 類型的新對(duì)象創(chuàng)建 unique_ptr 并將其插入到 ObjectArray 類型的對(duì)象中的語法是什么?
What is the syntax to create a unique_ptr to a new object of type Class1 and insert it into an object of type ObjectArray?
推薦答案
首先，如果它是映射而不是數(shù)組，我不會(huì)稱它為 ObjectArray.
As a first remark, I wouldn't call it ObjectArray if it is a map and not an array.
無論如何，你可以這樣插入對(duì)象:
Anyway, you can insert objects this way:
ObjectArray myMap;
myMap.insert(std::make_pair(0, std::unique_ptr<Class1>(new Class1())));
或者這樣:
ObjectArray myMap;
myMap[0] = std::unique_ptr<Class1>(new Class1());
這兩種形式的區(qū)別在于，如果鍵 0 已經(jīng)存在于映射中，前一種將失敗，而第二種形式會(huì)用新的值覆蓋其值.
The difference between the two forms is that the former will fail if the key 0 is already present in the map, while the second one will overwrite its value with the new one.
在 C++14 中，您可能希望使用 std::make_unique() 而不是從 new 表達(dá)式構(gòu)造 unique_ptr .例如:
In C++14, you may want to use std::make_unique() instead of constructing the unique_ptr from a new expression. For instance:
myMap[0] = std::make_unique<Class1>();
這篇關(guān)于C ++在地圖中插入unique_ptr的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！