C ++在地图中插入unique_ptr
我有一个 ObjectArray
typedef map<int64_t, std::unique_ptr<Class1>> ObjectArray;
为 Class1 类型的新对象创建 unique_ptr 并将其插入到 ObjectArray 类型的对象中的语法是什么?
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?
推荐答案
首先，如果它是映射而不是数组，我不会称它为 ObjectArray.
As a first remark, I wouldn't call it ObjectArray if it is a map and not an array.
无论如何，你可以这样插入对象:
Anyway, you can insert objects this way:
ObjectArray myMap;
myMap.insert(std::make_pair(0, std::unique_ptr<Class1>(new Class1())));
或者这样:
ObjectArray myMap;
myMap[0] = std::unique_ptr<Class1>(new Class1());
这两种形式的区别在于，如果键 0 已经存在于映射中，前一种将失败，而第二种形式会用新的值覆盖其值.
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() 而不是从 new 表达式构造 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>();
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