How can I iterate over an enum?

by

The typical way is as follows:

enum Foo {
  One,
  Two,
  Three,
  Last
};

for ( int fooInt = One; fooInt != Last; fooInt++ )
{
   Foo foo = static_cast<Foo>(fooInt);
   // ...
}

Please note, the enum Last is meant to be skipped by the iteration. Utilizing this “fake” Last enum, you don’t have to update your terminating condition in the for loop to the last “real” enum each time you want to add a new enum.
If you want to add more enums later, just add them before Last. The loop in this example will still work.

Of course, this breaks down if the enum values are specified:

enum Foo {
  One = 1,
  Two = 9,
  Three = 4,
  Last
};

This illustrates that an enum is not really meant to iterate through. The typical way to deal with an enum is to use it in a switch statement.

switch ( foo )
{
    case One:
        // ..
        break;
    case Two:  // intentional fall-through
    case Three:
        // ..
        break;
    case Four:
        // ..
        break;
     default:
        assert( ! "Invalid Foo enum value" );
        break;
}

If you really want to enumerate, stuff the enum values in a vector and iterate over that. This will properly deal with the specified enum values as well.

More Related Contents:

  1. c++ Making a code that displays equations and keep getting the “expression must have integral or unscoped enum type” error
  2. Why is enum class preferred over plain enum?
  3. Is there a simple way to convert C++ enum to string?
  4. How to use enums as flags in C++?
  5. C++: Print out enum value as text
  6. Base enum class inheritance
  7. C++ string to enum
  8. Should I use #define, enum or const?
  9. Are C++ enums signed or unsigned?
  10. Allow for Range-Based For with enum classes?
  11. String to enum in C++
  12. Is it possible to determine if a type is a scoped enumeration type?
  13. How can I output the value of an enum class in C++11
  14. What is the underlying type of a c++ enum?
  15. Extending enums in C++?
  16. The usage of anonymous enums
  17. Pros and cons of using nested C++ classes and enumerations?
  18. Difference between Enum and Define Statements
  19. How to use C++11 enum class for flags
  20. How to check if enum value is valid?
  21. Detect when multiple enum items map to same value
  22. Enum vs Strongly typed enum
  23. Why do you use typedef when declaring an enum in C++?
  24. what is the size of an enum type data in C++?
  25. Equivalent of “using namespace X” for scoped enumerations?
  26. generating random enums
  27. namespaces for enum types – best practices
  28. Do C++ enums Start at 0?
  29. Why must an enumeration’s size be provided when it is forward declared?
  30. How can I extend a lexical cast to support enumerated types?

Leave a Comment