\documentclass{article}
\usepackage{algorithm}% http://ctan.org/pkg/algorithms
\usepackage{algpseudocode}% http://ctan.org/pkg/algorithmicx
\begin{document}

% https://tex.stackexchange.com/questions/229355/algorithm-algorithmic-algorithmicx-algorithm2e-algpseudocode-confused
% https://en.wikibooks.org/wiki/LaTeX/Algorithms

\begin{algorithm}
\caption{Naive  byte array to DNA encode}
\begin{algorithmic}[1]
\Procedure{EncodeToDNASequence}{$name$}
   \State $fp\gets open(name)$
   \State $en\gets null$
   \While{$fp\not=EOF$}
        \State $c\gets buf[0]$\Comment{Read 1 byte from buffer}
        \State $b\gets sprintf("08b", c)$\Comment{Convert to string binary}
        \For{\texttt{e in range[0,2,4,6]}}
            \If {$e[0] = 48$ $1$ and $e[1] = 48$}\Comment{0x00 - A (Adenine)}
                \State $en\gets en + `A`$
            \EndIf
            \If {$e[0] = 48$ $1$ and $e[1] = 49$}\Comment{0x01 - G (Guanine)}
                \State $en\gets en + `G`$
            \EndIf
            \If {$e[0] = 49$ $1$ and $e[1] = 48$}\Comment{0x10 - C (Cytosine)}
                \State $en\gets en + `C`$
            \EndIf
            \If {$e[0] = 49$ $1$ and $e[1] = 49$}\Comment{0x11 - T (Thymine)}
                \State $en\gets en + `T`$
            \EndIf
        \EndFor
   \EndWhile
   \State \textbf{return} $en$\Comment{Return string DNA sequence}
\EndProcedure
\end{algorithmic}
\end{algorithm}

%\begin{algorithm}
%\caption{Euclid’s algorithm}\label{euclid}
%\begin{algorithmic}[1]
%\Procedure{Euclid}{$a,b$}\Comment{The g.c.d. of a and b}
%   \State $r\gets a\bmod b$
%   \While{$r\not=0$}\Comment{We have the answer if r is 0}
%      \State $a\gets b$
%      \State $b\gets r$
%      \State $r\gets a\bmod b$
%   \EndWhile\label{euclidendwhile}
%   \State \textbf{return} $b$\Comment{The gcd is b}
%\EndProcedure
%\end{algorithmic}
%\end{algorithm}

\end{document}