assignment of array

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Array declaration.

Declares an object of array type.

[ edit ] Syntax

An array declaration is any simple declaration whose declarator has the form

A declaration of the form T a [ N ] ; , declares a as an array object that consists of N contiguously allocated objects of type T . The elements of an array are numbered 0 , …, N - 1 , and may be accessed with the subscript operator [] , as in a [ 0 ] , …, a [ N - 1 ] .

Arrays can be constructed from any fundamental type (except void ), pointers , pointers to members , classes , enumerations , or from other arrays of known bound (in which case the array is said to be multi-dimensional). In other words, only object types except for array types of unknown bound can be element types of array types. Array types of incomplete element type are also incomplete types.

There are no arrays of references or arrays of functions.

Applying cv-qualifiers to an array type (through typedef or template type manipulation) applies the qualifiers to the element type, but any array type whose elements are of cv-qualified type is considered to have the same cv-qualification.

When used with new[]-expression , the size of an array may be zero; such an array has no elements:

[ edit ] Assignment

Objects of array type cannot be modified as a whole: even though they are lvalues (e.g. an address of array can be taken), they cannot appear on the left hand side of an assignment operator:

[ edit ] Array-to-pointer decay

There is an implicit conversion from lvalues and rvalues of array type to rvalues of pointer type: it constructs a pointer to the first element of an array. This conversion is used whenever arrays appear in context where arrays are not expected, but pointers are:

[ edit ] Multidimensional arrays

When the element type of an array is another array, it is said that the array is multidimensional:

Note that when array-to-pointer decay is applied, a multidimensional array is converted to a pointer to its first element (e.g., a pointer to its first row or to its first plane): array-to-pointer decay is applied only once.

[ edit ] Arrays of unknown bound

If expr is omitted in the declaration of an array, the type declared is "array of unknown bound of T", which is a kind of incomplete type , except when used in a declaration with an aggregate initializer :

Because array elements cannot be arrays of unknown bound, multidimensional arrays cannot have unknown bound in a dimension other than the first:

If there is a preceding declaration of the entity in the same scope in which the bound was specified, an omitted array bound is taken to be the same as in that earlier declaration, and similarly for the definition of a static data member of a class:

References and pointers to arrays of unknown bound can be formed, but cannot (until C++20) and can (since C++20) be initialized or assigned from arrays and pointers to arrays of known bound. Note that in the C programming language, pointers to arrays of unknown bound are compatible with pointers to arrays of known bound and are thus convertible and assignable in both directions.

Pointers to arrays of unknown bound cannot participate in pointer arithmetic and cannot be used on the left of the subscript operator , but can be dereferenced.

[ edit ] Array rvalues

Although arrays cannot be returned from functions by value and cannot be targets of most cast expressions, array prvalues may be formed by using a type alias to construct an array temporary using brace-initialized functional cast .

Array xvalues may be formed directly by accessing an array member of a class rvalue or by using std::move or another cast or function call that returns an rvalue reference.

[ edit ] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[ edit ] See also

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Array Variable Assignment in Java

An array is a collection of similar types of data in a contiguous location in memory. After Declaring an array we create and assign it a value or variable. During the assignment variable of the array things, we have to remember and have to check the below condition.

1. Element Level Promotion

Element-level promotions are not applicable at the array level. Like a character can be promoted to integer but a character array type cannot be promoted to int type array.

2. For Object Type Array

In the case of object-type arrays, child-type array variables can be assigned to parent-type array variables. That means after creating a parent-type array object we can assign a child array in this parent array.

When we assign one array to another array internally, the internal element or value won’t be copied, only the reference variable will be assigned hence sizes are not important but the type must be matched.

3. Dimension Matching

When we assign one array to another array in java, the dimension must be matched which means if one array is in a single dimension then another array must be in a single dimension. Samely if one array is in two dimensions another array must be in two dimensions. So, when we perform array assignment size is not important but dimension and type must be matched.