27.3.3. C++ initialization types
OMG this is hell, understand when primitive variables are initialized or not:
Intuition:
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direct initialization: a constructor called explicitly with at least one argument: https://en.cppreference.com/w/cpp/language/direct_initialization
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default initialization: does not initialize primitive types: https://en.cppreference.com/w/cpp/language/default_initialization
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value initialization: maybe initializes primitive types: https://en.cppreference.com/w/cpp/language/value_initialization
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zero initialization: initializes primitive types
Good rule:
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initialize every single variable explicitly to prevent the risk of having uninitialized variables due to programmer error (which is easy to get wrong due to insane rules)
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if you don’t define your own default constructor, always
= deleteit instead. This prevents the possibility that variables will be assigned twice due to zero initialization