C++_Reminders - RicoJia/notes GitHub Wiki
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dynamic_castcan be used to check if we get a derived. base -> derived ædep```cpp //In an array of ptr MyChild* = dynamic_cast<MyChild*> (ptr); //this will succeed if ptr points to a child class object, or it will return null if ptr points to a base class object. if(!ptr){...} //use !ptr here, I am not sure what type this is?
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## Type and Templates
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1. dependent typenames need typename at the front:
- ```typename std::list<T>``` because there's a T in the list
2. Reminder: ```emplace_back``` doesn't work with ```std::initializer_list```
- ```emplace_back``` is a templated function uses perfect forwarding. template deduction does not deduce ```{}``` into ```std::intializer```. But it works with ```std::initializer_list<TYPE>```
- ```std::vector<double>``` works with ```std::initializer_list<double>``` because there's ctor ```std::vector<double>(std::initializer_list<double>)```
- ```std::initializer_list<int>``` does not implicitly convert to ```std::initializer_list<double>```
3. Reminder: const member functions only work with ```const_iterator```
```cpp
// if returning iterator, then see error: __normal_iterator<const int*,[...]>’ to ‘__normal_iterator<int*,[...]>
std::vector<int>::const_iterator foo() const{
return vec_.cbegin();
}
```
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## Pointers
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1. ```unique_ptr.reset();``` destroys the object
2. Reminder: **Tricky Bug: accessing a freed memory: it might give you the same value**
```cpp
ptr = node;
free(node);
cout<<ptr;
```