D Documentation  
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  1. Introduction
    1. A simple tutorial
    2. Switching to D
    3. An advanced tutorial
  2. Language Reference
    1. General syntax
    2. Statements
    3. Types
      1. void
      2. bit
      3. Integer data types
      4. Floatingpoint data types
      5. Character data types
      6. Derived data types
      7. User Defined Types
        1. Classes
      8. Delegates
    4. Error Handling
    5. Memory Management
  3. Std. runtime library (Phobos)
    1. std.base64
    2. std.boxer
    3. std.compiler
    4. std.conv
    5. std.ctype
    6. std.date
    7. std.file
    8. std.format
    9. std.gc
    10. std.intrinsic
    11. std.math
    12. std.md5
    13. std.mmfile
    14. std.outbuffer
    15. std.path
    16. std.process
    17. std.random
    18. std.recls
    19. std.regexp
    20. std.socket
    21. std.socketstream
    22. std.stdint
    23. std.stdio
    24. std.stream
    25. std.string
    26. std.system
    27. std.thread
    28. std.uri
    29. std.utf
    30. std.zip
    31. std.zlib
  4. Libraries and Tools
    1. mango
    2. Build
  5. Related Links
  6. About this documentation
User Defined Types
  • alias
  • typedef
  • enum
  • struct
  • union
  • class

Alias
An alias is simply an extra name for a type. It does not matter what kind of a type it is, buildin or user.

An alias may also be an alias for a function or namespace.

alias int thisisint;
thisisint x = 5;
int function(int u) {}
int function(thisisint) {} // error; conflicts with int version of function
alias function myfunction;
myfunction(x); // this will call 'function'


This will just create an int with value 5. 'thisisint' will be fully treated as an int; when doing overloading one must take care of this. If you want it to behave as though it's it's own type instead of a copy reference, you must use typedef.

Typedef
A typedef is almost the same as an alias, though it may not be used to regroup/label functions or namespaces. Typedefs will act as though it's it's own type, so if you do

typedef int myint;
void function(int x) { }
void function(myint x) { }
myint i = 4;
int z = 5;
function(i); // the 'myint' version will be called
function(z); // the int version will be called


Enum
An enum is an emuration of constants. An enum may be derived from a basic type to assign to it a size in bytes (equal to the type derived). Enums are useful when creating certain properties.

enum Day : int { // where int is derived type, may be left out
  Monday,
  Thuesday,
  Wednesday
}
printf("%d", Day.Monday); // will print 0
printf("%d", Day.Thuesday); // will print 1]
Day myDay = Day.Monday;


Usually everytime you add an element, the element value is increased by one. You may also be explicit about the constant value assigned to an element:

enum Day {
  Monday = 10,
  Thuesday // will be 11
}
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