Guide to LaTeX (4th Edition) (Tools and Techniques

98 Chapter 4. Displayed Text
If a p-type column contains \raggedright or \centering, the \\ forces a
! new line within the column entry and not the end of the whole row. If this occurs
in the last column, then \\ cannot be used to terminate the row; instead one
must use \tabularnewline to end such a row.
Since a table is a vertical box of the same sort as parbox and minipage,
it may be positioned horizontally with other boxes or text (see examples
in Section 4.7.3). In particular, the table must be enclosed within
\begin{center} table \end{center}
in order to center it on the page.
4.8.2 Table style parameters
There are a number of style parameters used in generating tables which L AT E X sets
! to standard values. These may be altered by the user, either globally within the
preamble or locally inside an environment. They should not be changed within
the tabular environment itself.
\tabcolsep is half the width of the spacing that is inserted between columns
in the tabular and tabular* environments;
\arraycolsep is the corresponding half intercolumn spacing for the array
environment;
\arrayrulewidth is the thickness of the vertical and horizontal lines within a
table;
\doublerulesep is the separation between the lines of a double rule.
Changes in these parameters can be made with the \setlength command as
usual. For example, to make the line thickness to be 0.5 mm, give \setlength
{\arrayrulewidth}{0.5mm}. Furthermore, the parameter
\arraystretch can be used to change the distance between the rows of a table.
This is a multiplying factor, with a standard value of 1. A value of 1.5
means that the inter-row spacing is increased by 50%. A new value is set
by redefining the parameter with the command
4.8.3 Table examples
\renewcommand{\arraystretch}{factor}
Creating tables is much easier in practice than it would seem from the
above list of formatting possibilities. This is best illustrated with a few
examples.
The simplest table consists of a row of columns in which the text
entries are either centered or justified to one side. The column widths,
the spacing between the columns, and thus the entire width of the table
are automatically calculated.