Bahasa pengaturcaraan D

Contoh

Kata kekunci diwarnakan biru, rentetan pula merah, manakala ulasan diwarnakan hijau.

Contoh 1

Atur cara contoh berikut memaparkan argumen-argumen baris perintahnya.
Fungsi main ialah titik masuk bagi atur cara D, dan args
ialah tatasusunan rentetan mewakili argumen-argumen baris perintah.
Rentetan dalam D ialah sebuah tatasusunan aksara yang diwakili oleh char[].
import std.stdio;       // for writefln()int main(char[][] args)
{
    foreach(i, a; args)
        writefln("args[%d] = '%s'", i, a);
    return 0;
}
Kenyataan foreach boleh mengulang apa jua koleksi, di sini ia menghasilkan tatasusunan indeks (i) dan nilai (a) daripada tatasusunan
args. Jenis bagi indeks i dan nilai a diketahui melalui jeni bagi tatasusunan args.

Contoh 2

Berikut menunjukkan penggunaan tatasusunan bersekutu bagi membentuk struktur data yang lebih kompleks
import std.stdio;       // for writefln()int main(char[][] args)
{
    // Declare an associative array with string keys and
    // arrays of strings as data
    char[][] [char[]] container;

    // Add some people to the container and let them carry some items
    container["Anya"] ~= "scarf";
    container["Dimitri"] ~= "tickets";
    container["Anya"] ~= "puppy";

    // Iterate over all the persons in the container
    foreach (char[] person, char[][] items; container)
        display_item_count(person, items);
    return 0;
}

void display_item_count(char[] person, char[][] items)
{
    writefln(person, " is carrying ", items.length, " items.");
}

Contoh 3

Contoh yang mempunyai banyak anotasi berikut menonjolkan banyak perbezaan berbanding C++, sambil masih mengekalkan beberapa aspek C++.
#!/usr/bin/dmd -run
/* sh style script syntax is supported! */
/* Hello World in D
 * To compile:
 *   dmd hello.d
 * or to optimize:
 *   dmd -O -inline -release hello.d
 * or to get generated documentation:
 *   dmd hello.d -D
 */import std.stdio;                        // References to  commonly used I/O routines.int main(char[][] args)                 
{
    // 'writefln' (Write-Formatted-Line) is the type-safe 'printf'
    writefln("Hello World, "             // automatic concatenation of string literals
             "Reloaded");

    // Strings are denoted as a dynamic array of chars 'char[]'
    // auto type inference and built-in foreach
    foreach(argc, argv; args)
    {
        auto cl = new CmdLin(argc, argv);                  // OOP is supported
writefln(cl.argnum, cl.suffix, " arg: %s", cl.argv); // user-defined class properties.

delete cl;               // Garbage Collection or explicit memory management - your choice
    }

    // Nested structs, classes and functions
    struct specs
    {
// all vars automatically initialized to 0 at runtime
int count, allocated;
// however you can choose to avoid array initialization
int[10000] bigarray = void;
    }

    specs argspecs(char[][] args)
    // Optional (built-in) function contracts.
    in
    {
assert(args.length > 0);                   // assert built in
    }
    out(result)
    {
assert(result.count == CmdLin.total);
assert(result.allocated > 0);
    }
    body
    {
specs* s = new specs;
// no need for '->'
s.count = args.length;  // The 'length' property is number of elements.
s.allocated = typeof(args).sizeof; // built-in properties for native types
foreach(arg; args)
    s.allocated += arg.length * typeof(arg[0]).sizeof;
return *s;
    }

    // built-in string and common string operations, eg. '~' is concatenate.
    char[] argcmsg  = "argc = %d";
    char[] allocmsg = "allocated = %d";
    writefln(argcmsg ~ ", " ~ allocmsg,
    argspecs(args).count,argspecs(args).allocated);
    return 0;
}

/**
 * Stores a single command line argument.
 */class CmdLin
{
    private
    {
int _argc;
char[] _argv;
static uint _totalc;
    }

    public:
/**
 * Object constructor.
 * params:
 *   argc = ordinal count of this argument.
 *   argv = text of the parameter
 */
this(int argc, char[] argv)
{
    _argc = argc + 1;
    _argv = argv;
    _totalc++;
}

~this() // Object destructor
{
    // Doesn't actually do anything for this example.
}

int argnum() // A property that returns arg number
{
    return _argc;
}

char[] argv() // A property that returns arg text
{
    return _argv;
}

wchar[] suffix() // A property that returns ordinal suffix
{
    wchar[] suffix; // Built in Unicode strings (UTF-8, UTF-16, UTF-32)
    switch(_argc)
    {
case 1:
    suffix = "st";
    break;
case 2:
    suffix = "nd";
    break;
case 3:
    suffix = "rd";
    break;
default:  // 'default' is mandatory with "-w" compile switch.
    suffix = "th";
    }
    return suffix;
}

/**
         * A static property, as in C++ or Java,
         * applying to the class object rather than instances.
         * returns: The total number of commandline args added.
         */
static typeof(_totalc) total()
{
    return _totalc;
}

// Class invariant, things that must be true after any method is run.
invariant
{
    assert(_argc > 0);
    assert(_totalc >= _argc);
}
}