STL中 map的count 方法（Finds the number of elements matching a specified key）

size_type count(key_type key);

Remarks

The member function returns the number of 
elements in the controlled sequence that have 
equivalent ordering with key. You use it to 
determine the number of elements currently in 
the controlled sequence that match a 
specified key.

标签：count,map,elements,sequence,number,key,specified,type
来源： https://blog.csdn.net/SeaEddies/article/details/121835485