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So, PHP can have non-consecutively numerically indexed arrays. The keys have to be of integer (floating point numbers are truncated to integer) or string type, while values can be of arbitrary types, including other arrays and objects. The arrays are heterogeneous: a single array can have keys of different types.
Objects, in the sense of object-oriented programming, belong to reference types. Assigning to a variable of reference type simply copies the reference, whereas assigning to a variable of value type copies the value. This applies to all kinds of variables, including local variables, fields of objects, and array elements.
Some people (including Guido van Rossum himself) have called this parameter-passing scheme "call by object reference". An object reference means a name, and the passed reference is an "alias", i.e. a copy of the reference to the same object, just as in C/C++. The object's value may be changed in the called function with the "alias", for example:
A reference to Y(2) is a reference to X(2,2), and so on. A slice, called a cross-section, of an array can be referred to by using asterisk as the subscript for one or more dimensions. The following code sets all the elements in the first column of X to zero. One or more subscripts can be specified by asterisks in an expression.
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.
The specific problem is: This article's reference section contains many footnotes, but lists no external references or sources. Please help improve this article if you can. ( June 2013 ) ( Learn how and when to remove this message )
array[i] means element number i, 0-based, of array which is translated into *(array + i). The last example is how to access the contents of array. Breaking it down: array + i is the memory location of the (i) th element of array, starting at i=0; *(array + i) takes that memory address and dereferences it to access the value.
Type aliasing is a feature in some programming languages that allows creating a reference to a type using another name. It does not create a new type hence does not increase type safety . It can be used to shorten a long name.