std::map Memory Issue

[TheoLogic]

It is stupid, it shouldn't add a value in when you're reading from it. They only did this because it has to return a pointer that can be gotten or set:

a = map[2]
map[2] = a

So it's a result of a limitation of the C++ language, because none of this stuff was implemented when they originally designed the thing. Which is why we call C++ an octopus made by nailing extra legs to a dog.

 

It is not stupid, and clearly defined in the standard: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf (23.4.4.3 map element access)

 

 

T& operator[](key_type&& x);

* Effects: If there is no key equivalent to x in the map, inserts value_type(std::move(x), T()) into

the map.

* Requires: mapped_type shall be DefaultConstructible.

* Returns: A reference to the mapped_type corresponding to x in *this.

* Complexity: logarithmic.

[Josh]

Thanks to the C++ guys for the tips.