You should use new when you wish an object to remain in existence until you delete it. If you do not use new then the object will be destroyed when it goes out of scope. Some examples of this are: void foo() { Point p = Point(0,0); } // p is now destroyed. for (…) … Read more
Both do different things. The first creates an object with automatic storage duration. It is created, used, and then goes out of scope when the current block ({ … }) ends. It’s the simplest way to create an object, and is just the same as when you write int x = 0; The second creates … Read more
What is happening When you write T t; you’re creating an object of type T with automatic storage duration. It will get cleaned up automatically when it goes out of scope. When you write new T() you’re creating an object of type T with dynamic storage duration. It won’t get cleaned up automatically. You need … Read more
One question that the answers given so far don’t seem to address: if the runtime libraries (not the OS, really) can keep track of the number of things in the array, then why do we need the delete[] syntax at all? Why can’t a single delete form be used to handle all deletes? The answer … Read more
I do that the following way: NSError *error; NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; // Get documents folder NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@”/MyFolder”]; if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath]) [[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:&error]; //Create folder
It’s a surprisingly little-known feature of C++ (as evidenced by the fact that no-one has given this as an answer yet), but it actually has special syntax for value-initializing an array: new int[10](); Note that you must use the empty parentheses — you cannot, for example, use (0) or anything else (which is why this … Read more
It will throw a FileNotFoundException if the file doesn’t exist and cannot be created (doc), but it will create it if it can. To be sure you probably should first test that the file exists before you create the FileOutputStream (and create with createNewFile() if it doesn’t): File yourFile = new File(“score.txt”); yourFile.createNewFile(); // if … Read more
The override modifier may be used on virtual methods and must be used on abstract methods. This indicates for the compiler to use the last defined implementation of a method. Even if the method is called on a reference to the base class it will use the implementation overriding it. public class Base { public … Read more
The C++ FAQ Lite has a entry specifically for this https://isocpp.org/wiki/faq/freestore-mgmt#delete-this I think this quote sums it up nicely As long as you’re careful, it’s OK for an object to commit suicide (delete this).
Quoting David Flanagan1: As a special case, for the new operator only, JavaScript simplifies the grammar by allowing the parenthesis to be omitted if there are no arguments in the function call. Here are some examples using the new operator: o = new Object; // Optional parenthesis omitted here d = new Date(); … Personally, … Read more