Tutorial for the Brainfuck programming language.

Brainfuck is a minimal programming language that is rather difficult
to wrap one's head around. It only uses the characters +-[],.><

brainfuck.html.markdown

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+---
+language: brainfuck
+contributors:
+    - ["Prajit Ramachandran", "http://prajitr.github.io"]
+---
+
+Brainfuck is an extremely minimal programming language (just 8 commands) and 
+is Turing complete.
+
+```
+Any character not "><+-.,[]" (excluding quotation marks) is ignored.
+
+Brainfuck is represented by an array with 30,000 cells initialized to zero
+and a data pointer pointing at the current cell.
+
+There are eight commands:
++ : Increments the value at the current cell by one.
+- : Decrements the value at the current cell by one.
+> : Moves the data pointer to the next cell (cell on the right).
+< : Moves the data pointer to the previous cell (cell on the left).
+. : Prints the ASCII value at the current cell (i.e. 65 = 'A').
+, : Reads a single input character into the current cell.
+[ : If the value at the current cell is zero, skips to the corresponding ] .
+    Otherwise, move to the next instruction.
+] : If the value at the current cell is zero, move to the next instruction.
+    Otherwise, move backwards in the instructions to the corresponding [ .
+
+[ and ] form a while loop. Obviously, they must be balanced.
+
+Let's look at some basic Brainfuck programs.
+
+++++++ [ > ++++++++++ < - ] > +++++ .
+
+This program prints out the letter 'A'. First, it increments cell #1 to 6.
+Cell #1 will be used for looping. Then, it enters the loop ([) and moves
+to cell #2. It increments cell #2 10 times, moves back to cell #1, and
+decrements cell #1. This loop happens 6 times (it takes 6 decrements for
+cell #1 to reach 0, at which point it skips to the corresponding ] and
+continues on).
+
+At this point, we're on cell #1, which has a value of 0, while cell #2 has a
+value of 60. We move on cell #2, increment 5 times, for a value of 65, and then
+print cell #2's value. 65 is 'A' in ASCII, so 'A' is printed to the terminal.
+
+
+, [ > + < - ] > .
+
+This program reads a character from the user input, copies the character into
+another cell, and prints out the same character.
+
+, reads in a character from the user into cell #1. Then we start a loop. Move
+to cell #2, increment the value at cell #2, move back to cell #1, and decrement
+the value at cell #1. This continues on until cell #1 is 0, and cell #2 holds
+cell #1's old value. Because we're on cell #1 at the end of the loop, move to
+cell #2, and then print out the value in ASCII.
+
+Also keep in mind that the spaces are purely for readibility purposes. You 
+could just as easily write it as
+
+,[>+<-]>.
+
+
+Try and figure out what this program does:
+
+,>,< [ > [ >+ >+ << -] >> [- << + >>] <<< -] >>  
+
+This program takes two numbers for input, and multiplies them.
+
+The gist is it first reads in two inputs. Then it starts the outer loop,
+conditioned on cell #1. Then it moves to cell #2, and starts the inner
+loop conditioned on cell #2, incrementing cell #3. However, there comes a 
+problem: at the end of the inner loop, cell #2 is zero. To solve this problem,
+we also increment cell #4, and then recopy cell #4 into cell #2.
+```
+
+And that's Brainfuck. Not that hard, eh? For fun, you can write your own 
+Brainfuck programs, or you can write a Brainfuck interpreter in another 
+language. The interpreter is fairly simple to implement, but if you're a
+masochist, trying writing a Brainfuck interpreter... in Brainfuck.