Keyword typedef provides a mechanism for creating synonyms (or aliases) for previously defined data types. Names for structure types are often defined with typedef to more readable type names. For example, the statement

typedef Card* CardPtr;

defines the new type name CardPtr as a synonym for type Card*. Creating a new name with typedef does not create a new type; typedef simply creates a new type name that can then be used in the program as an alias for an existing type name.

C++11 added the keyword using as another mechanism for creating type aliases.The following declaration is equivalent to the typedef above:

using CardPtr = Card*;

This feature was added to fix problems with typedef in template programming.