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
[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
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
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