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For every type T, except void and function types, there exist the types "array of N elements of type T". An array is a collection of values, all of the same type, stored contiguously in memory. An array of size N is indexed by integers from 0 up to and including N−1. Here is a brief example:
In other languages, variables are often initialized to known values when created. Examples include: VHDL initializes all standard variables into special 'U' value. It is used in simulation, for debugging, to let the user to know when the don't care initial values, through the multi-valued logic, affect the output.
For a multidimensional array, the element with indices i,j would have address B + c · i + d · j, where the coefficients c and d are the row and column address increments, respectively. More generally, in a k-dimensional array, the address of an element with indices i 1, i 2, ..., i k is B + c 1 · i 1 + c 2 · i 2 + … + c k · i k. For ...
C struct data types may end with a flexible array member [1] with no specified size: struct vectord { short len ; // there must be at least one other data member double arr []; // the flexible array member must be last // The compiler may reserve extra padding space here, like it can between struct members };
Therefore, although function calls in C use pass-by-value semantics, arrays are in effect passed by reference. The total size of an array x can be determined by applying sizeof to an expression of array type. The size of an element can be determined by applying the operator sizeof to any dereferenced element of an array A, as in n = sizeof A[0].
When no initial value seems appropriate, for example, when one wants to fold the function which computes the maximum of its two parameters over a non-empty list to get the maximum element of the list, there are variants of foldr and foldl which use the last and first element of the list respectively as the initial value.
In C and C++ arrays do not support the size function, so programmers often have to declare separate variable to hold the size, and pass it to procedures as a separate parameter. Elements of a newly created array may have undefined values (as in C), or may be defined to have a specific "default" value such as 0 or a null pointer (as in Java).
The following C99 function allocates a variable-length array of a specified size, fills it with floating-point values, and then passes it to another function for processing. Because the array is declared as an automatic variable, its lifetime ends when read_and_process() returns.