What is the default value for C++ class members

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There are no differences between structs and classes in this regard in C++. They all are called just class types.

Members of class types have no default values in general case. In order to for a class member to get a deterministic value it has to be initialized, which can be done by

  • Default constructor of the member itself
  • Constructor initializer list of the enclosing class
  • Explicitly specified initializer for object of the enclosing class (that includes value-initialization and initialization with aggregate initializer).

Additionally, all objects with static storage duration are zero-initialized at the program startup.

Aside from the above cases, class members, once again, have no default values and will initially contain unpredictable garbage values.

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