如何从指针访问 C++ 映射的元素？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/1236485/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to access elements of a C++ map from a pointer?
提问by Greg Hewgill
Simple question but difficult to formulate for a search engine: if I make a pointer to a map object, how do I access and set its elements? The following code does not work.
一个简单的问题，但很难为搜索引擎制定：如果我创建一个指向地图对象的指针，我如何访问和设置它的元素？以下代码不起作用。
map<string, int> *myFruit;
myFruit["apple"] = 1;
myFruit["pear"] = 2;
回答by Greg Hewgill
You can do this:
你可以这样做：
(*myFruit)["apple"] = 1;
or
或者
myFruit->operator[]("apple") = 1;
or
或者
map<string, int> &tFruit = *myFruit;
tFruit["apple"] = 1;
回答by swongu
myFruitis a pointer to a map. If you remove the asterisk, then you'll have a map and your syntax following will work.
myFruit是一个指向地图的指针。如果您删除星号，那么您将拥有一张地图，并且您的语法将起作用。
Alternatively, you can use the dereferencing operator (*) to access the map using the pointer, but you'll have to create your map first:
或者，您可以使用解引用运算符 ( *) 通过指针访问地图，但您必须先创建您的地图：
map<string, int>* myFruit = new map<string, int>() ;
回答by rpjohnst
map<string, int> *myFruit;
(*myFruit)["apple"] = 1;
(*myFruit)["pear"] = 2;
would work if you need to keep it as a pointer.
如果您需要将其保留为指针会起作用。
