Time for action – using the array package

We shall modify the table definition to set our input columns in the typewriter font. At the same time, we will insert a column on the left, standing for our command type:

1. Extend the preamble of our example by defining a command \normal. It shall use \multicolumn to produce an l cell, no matter what the column formatting is:

   \documentclass{article}
   \usepackage{array}
   \usepackage{booktabs}
   \newcommand{\head}[1]{\textnormal{\textbf{#1}}}
   \newcommand{\normal}[1]{\multicolumn{1}{l}{#1}}
   \begin{document}

2. As \verb cannot be used in table headers, we shall use \ttfamily. Preceding it with \textbackslash is enough for our purposes. Use >{…} to insert it twice. Then add <{Example text} to the last column to save typing work:

   \begin{tabular}{@{}l*2{>{\textbackslash\ttfamily}l}l%
   <{Example text}@{}}
     \toprule[1.5pt]
   & \multicolumn{2}{c}{\head{Input}} &
       \multicolumn{1}{c}{\head{Output}}\\

3. We'll use the \normal command to avoid the typewriter...