How to format "for loop" for printing a (pseudo) code listing

Question

I want to write a 'for' statement, but unsure how to do this with LaTeX. What I am trying to do is:

for k = 1, k++, while k < i

What is the proper (or at least a decent way) to write this in LaTeX?

Let me re-phrase:

I do not want to actually create a loop, I just want to print a line that will be the text of the beginning of a for-loop. I'm unsure how to do this.

Answer 1

If you're interested in typesetting algorithmic code, there are a number of choices. You can use a pseudocode environment algpseudocode offered by algorithmicx. Here's a short example from the algorithmicx documentation (with a pseudocode for loop added):

\documentclass{article}
\usepackage{algorithm}% http://ctan.org/pkg/algorithm
\usepackage{algpseudocode}% http://ctan.org/pkg/algorithmicx
\begin{document}
\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}
      \For{\texttt{<some condition>}}
        \State \texttt{<do stuff>}
      \EndFor
      \State \Return $b$\Comment{The gcd is b}
    \EndProcedure
  \end{algorithmic}
\end{algorithm}
\end{document}

The algorithms bundle supplied the algorithm floating environment.

Alternatively, the de-facto program typesetting package is listings. The examples, usage and language support is vast. An abundance of examples is contained within the listings documentation.

Answer 2

If you just want to print the statement, then something like

\[
\text{for $k = 1$, $k{+}{+}$, while $k < i$}
\]

will set it in a displayed format (remember to call \usepackage{amsmath} in the preamble). If it's as an item in an enumerate, then

\item for $k = 1$, $k{+}{+}$, while $k < i$

is sufficient.

The only subtle point is to enclose the + symbols between braces, in order to avoid undesired spacings.

Answer 3

\documentclass{article}
\usepackage{algorithm,algpseudocode}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\renewcommand{\algorithmicrequire}{\textbf{Input:}}
\renewcommand{\algorithmicensure}{\textbf{Output:}}

\begin{document}

\begin{algorithm}[H] 
\caption{Sum of Array Elements}
\label{alg:loop}
\begin{algorithmic}[1]
\Require{$A_{1} \dots A_{N}$} 
\Ensure{$Sum$ (sum of values in the array)}
\Statex
\Function{Loop}{$A[\;]$}
  \State {$Sum$ $\gets$ {$0$}}
    \State {$N$ $\gets$ {$length(A)$}}
    \For{$k \gets 1$ to $N$}                    
        \State {$Sum$ $\gets$ {$Sum + A_{k}$}}
    \EndFor
    \State \Return {$Sum$}
\EndFunction
\end{algorithmic}
\end{algorithm}

\end{document}

Answer 4

With the package algorithm2e, we can rewrite the example provided above like the following in LaTeX:

\usepackage[ruled,vlined,linesnumbered]{algorithm2e}
\begin{document}
\begin{algorithm}[H] 
\SetKwInOut{Input}{input}\SetKwInOut{Output}{output}
\Input{$A_{1} \dots A_{N}$}
\Output{$Sum$ (sum of values in the array)}
\DontPrintSemicolon
\caption{Sum of Array Elements}
\label{alg:loop}
\SetKwFunction{FLoop}{Loop}
\SetKwProg{Fn}{Function}{}{}
\BlankLine
\Fn{\FLoop{$A[;]$}}{
  \State {$Sum$ $\gets$ {$0$}} ;
    \State {$N$ $\gets$ {$length(A)$}} ;
    \For{$k \gets 1$ to $N$} {
        \State {$Sum$ $\gets$ {$Sum + A_{k}$}}
    }
    \KwRet {$Sum$}
}
\end{algorithm}
\end{document}

with the following output:

Answer 5

To the example given by Werner above. It did not work for me until I included braces as if I'm coding. Like this:

\For{\texttt{<some condition>}} {
        \State \texttt{<do stuff>}
      \EndFor
}