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The resulting object is called an object copy or simply copy of the original object. Copying is basic but has subtleties and can have significant overhead. There are several ways to copy an object, most commonly by a copy constructor or cloning. Copying is done mostly so the copy can be modified or moved, or the current value preserved.
In Java, the Object class contains the clone() method, which copies the object and returns a reference to that copied object. Since it is in the Object class, all classes defined in Java will have a clone method available to the programmer (although to function correctly it needs to be overridden at each level it is used). Cloning an object in ...
Using this technique, when a user asks the system to copy an object, it instead merely creates a new reference that still points to the same object. As soon as a user attempts to modify the object through a particular reference, the system makes a real copy, applies the modification to that, and sets the reference to refer to the new copy.
For example, strings and arrays are passed by reference, but when modified, they are duplicated if they have non-zero reference counts. This allows them to act as value types without the performance problems of copying on assignment or making them immutable. [8] In the Qt framework, many types are copy-on-write ("implicitly shared" in Qt's terms).
Rest parameters are similar to Javascript's arguments object, which is an array-like object that contains all of the parameters (named and unnamed) in the current function call. Unlike arguments, however, rest parameters are true Array objects, so methods such as .slice() and .sort() can be used on them directly.
String representation Object copy Value equality Object comparison Hash code Object ID Human-readable Source-compatible ABAP Objects — APL (Dyalog) ⍕x ⎕SRC x ⎕NS x: x = y — C++ x == y [52] pointer to object can be converted into an integer ID: C# x.ToString() x.Clone() x.Equals(y) x.CompareTo(y) x.GetHashCode()
In addition to support for vectorized arithmetic and relational operations, these languages also vectorize common mathematical functions such as sine. For example, if x is an array, then y = sin (x) will result in an array y whose elements are sine of the corresponding elements of the array x. Vectorized index operations are also supported.
adds a value into an object or array. Remove removes a value from an object or array. Replace replaces a value. Logically identical to using remove and then add. Copy copies a value from one path to another by adding the value at a specified location to another location. Move