D語言

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D語言是根據C語言改造的編程語言之一，由Digital Mars公司的Walter Bright製作。Walter Bright也是Symantec C++編譯器的作者。

[编辑] 特徵

• 可以任意地引進任何的文件。

[编辑] D語言中的Hello World程序

以下是D語言中的Hello World程序。

#!/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);

   }
}

[编辑] 外部链接

• D語言官方網站

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