break will exit the loop completely, continue will just skip the current iteration. For example: for (int i = 0; i < 10; i++) { if (i == 0) { break; } DoSomeThingWith(i); } The break will cause the loop to exit on the first iteration – DoSomeThingWith will never be executed. This here: for … Read more
Consider this code, #define WIDTH 300 enum econst { eWidth=300 }; const int Width=300; struct sample{}; int main() { sample s; int x = eWidth * s; //error 1 int y = WIDTH * s; //error 2 int z = Width * s; //error 3 return 0; } Obviously each multiplication results in compilation-error, but … Read more
There is one important, and useful, distinction between the two. Because .ForEach uses a for loop to iterate the collection, this is valid (edit: prior to .net 4.5 – the implementation changed and they both throw): someList.ForEach(x => { if(x.RemoveMe) someList.Remove(x); }); whereas foreach uses an enumerator, so this is not valid: foreach(var item in … Read more
I’m currently playing around with the Boost.Enum proposal from the Boost Vault (filename enum_rev4.6.zip). Although it was never officially submitted for inclusion into Boost, it’s useable as-is. (Documentation is lacking but is made up for by clear source code and good tests.) Boost.Enum lets you declare an enum like this: BOOST_ENUM_VALUES(Level, const char*, (Abort)(“unrecoverable problem”) … Read more
In python, using locals which returns a dictionary containing all the local bindings, thus, avoiding eval: >>> foo1 = “Hello world” >>> foo2 = “bar” >>> foo3 = {“1″:”a”, … “2”:”b”} >>> foo4 = “1+1” >>> import pprint >>> pprint.pprint(locals()) {‘__builtins__’: <module ‘__builtin__’ (built-in)>, ‘__doc__’: None, ‘__name__’: ‘__main__’, ‘foo1’: ‘Hello world’, ‘foo2’: ‘bar’, ‘foo3’: {‘1’: … Read more
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