You are removing the item during a foreach, yes? Simply, you can’t. There are a few common options here: use List<T> and RemoveAll with a predicate iterate backwards by index, removing matching items for(int i = list.Count – 1; i >= 0; i–) { if({some test}) list.RemoveAt(i); } use foreach, and put matching items into … Read more
The generally-preferred code for 10.5+/iOS. for (id object in array) { // do something with object } This construct is used to enumerate objects in a collection which conforms to the NSFastEnumeration protocol. This approach has a speed advantage because it stores pointers to several objects (obtained via a single method call) in a buffer … Read more
This is actually in my opinion an appropriate use case for 2.10 macros: you want access to information that you know the compiler has, but isn’t exposing, and macros give you a (reasonably) easy way to peek inside. See my answer here for a related (but now slightly out-of-date) example, or just use something like … Read more
Yes. As of Swift 3.0, if you need the index for each element along with its value, you can use the enumerated() method to iterate over the array. It returns a sequence of pairs composed of the index and the value for each item in the array. For example: for (index, element) in list.enumerated() { … Read more
One big difference is that Enumerations come with support for instantiating them from some name String. For example: object Currency extends Enumeration { val GBP = Value(“GBP”) val EUR = Value(“EUR”) //etc. } Then you can do: val ccy = Currency.withName(“EUR”) This is useful when wishing to persist enumerations (for example, to a database) or … Read more
Edit: this all changes in C# 5, with a change to where the variable is defined (in the eyes of the compiler). From C# 5 onwards, they are the same. Before C#5 The second is safe; the first isn’t. With foreach, the variable is declared outside the loop – i.e. Foo f; while(iterator.MoveNext()) { f … Read more
Enumerations on PHP
The collection used in foreach is immutable. This is very much by design. As it says on MSDN: The foreach statement is used to iterate through the collection to get the information that you want, but can not be used to add or remove items from the source collection to avoid unpredictable side effects. If … Read more
How to enumerate an enum