在map中插入unique_ptr的C ++ [英] C++ inserting unique_ptr in map
问题描述
我有一个C ++对象类型 ObjectArray
I have a C++ object of type ObjectArray
typedef map<int64_t, std::unique_ptr<Class1>> ObjectArray;
创建 unique_ptr
到类型 Class1
的新对象并将其插入到 ObjectArray
?
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
作为第一个注释,如果它是一个映射,我不会调用 ObjectArray
数组。
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())));
或这样:
ObjectArray myMap;
myMap[0] = std::unique_ptr<Class1>(new Class1());
两种形式之间的区别是前者将失败,如果键 0
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,您可以在地图中找到第一个可能需要使用 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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