There are two types of Arrays in D: static and dynamic.
Access to arrays of any kind is always bounds checked -
a failed range check yields a
RangeError which aborts the application.
The brave can disable this with the compiler flag
-boundschecks=off, in order
to squeeze the last cycles out of their binary.
Static arrays are stored on the stack if defined inside a function, or in static memory otherwise. They have a fixed, compile-time known length. A static array's type includes the fixed size:
arr's type is
int. Note that the size of the array is denoted
next to the type, and not after the variable name like in C/C++.
Dynamic arrays are stored on the heap and can be expanded
or shrunk at runtime. A dynamic array is created using a
and its length:
int size = 8; // run-time variable int arr = new int[size];
The type of
int, which is a slice. Slices
will be explained in more detail in the next section. Multi-dimensional
arrays can be created easily using the
auto arr = new int syntax.
Arrays can be concatenated using the
~ operator, which
will create a new dynamic array.
Mathematical operations can
be applied to whole arrays using a syntax like
c = a + b, for example.
This adds all elements of
b so that
c = a + b,
c = a + b, etc. It is also possible
to perform operations on a whole array with a single
a *= 2; // multiple all elements by 2 a %= 26; // calculate the modulo by 26 for all a's
These operations might be optimized by the compiler to use special processor instructions that do the operations in one go.
Both static and dynamic arrays provide the property
which is read-only for static arrays, but can be used in the case of
dynamic arrays to change its size dynamically. The
.dup creates a copy of the array.
When indexing an array through the
arr[idx] syntax, a special
$ symbol denotes an array's length. For example,
arr[$ - 1] references
the last element and is a short form for
arr[arr.length - 1].
Complete the function
encrypt to decrypt the secret message.
The text should be encrypted using Caesar encryption,
which shifts the characters in the alphabet using a certain index.
The to-be-encrypted text only contains characters in the range
which should make things easier.