D Programming Language

What is D?

D is a general purpose systems and applications programming language. It is a higher level language than C++, but retains the ability to write high performance code and interface directly with the operating system API's and with hardware. D is well suited to writing medium to large scale million line programs with teams of developers. D is easy to learn, provides many capabilities to aid the programmer, and is well suited to aggressive compiler optimization technology.

D is not a scripting language, nor an interpreted language. It doesn't come with a VM, a religion, or an overriding philosophy. It's a practical language for practical programmers who need to get the job done quickly, reliably, and leave behind maintainable, easy to understand code.

D is the culmination of decades of experience implementing compilers for many diverse languages, and attempting to construct large projects using those languages. D draws inspiration from those other languages (most especially C++) and tempers it with experience and real world practicality.

Example: wc

This program is the D version of the classic wc (wordcount) C program. It serves to demonstrate how to read files, slice arrays, and simple symbol table management with associative arrays.

import std.file;

int main (char[][] args)
{
    int w_total;
    int l_total;
    int c_total;

    printf ("   lines   words   bytes file/n");
    foreach (char[] arg; args[1 .. args.length])
    {
	char[] input;
	int w_cnt, l_cnt, c_cnt;
	int inword;

	input = cast(char[])std.file.read(arg);

	foreach (char c; input)
	{
	    if (c == '/n')
		++l_cnt;
	    if (c != ' ')
	    {
		if (!inword)
		{
		    inword = 1;
		    ++w_cnt;
		}
	    }
	    else
		inword = 0;
	    ++c_cnt;
	}
	printf ("%8lu%8lu%8lu %.*s/n", l_cnt, w_cnt, c_cnt, arg);
	l_total += l_cnt;
	w_total += w_cnt;
	c_total += c_cnt;
    }
    if (args.length > 2)
    {
	printf ("--------------------------------------/n%8lu%8lu%8lu total",
	    l_total, w_total, c_total);
    }
    return 0;
}