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   9 <title>Chapter 2: Basic Data Types and Operators</title>
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  15 <H1>Chapter 2: Basic Data Types and Operators</H1>
  16
  17 <p>The <dfn>type</dfn> of a variable
  18 determines what kinds of values it may take on.
  19 An <dfn>operator</dfn> computes new values out of old ones.
  20 An <dfn>expression</dfn> consists of variables, constants, and
  21 operators combined to perform some useful computation.
  22 In this chapter, we'll learn about C's basic types,
  23 how to
  24 write constants and
  25 declare variables of these types,
  26 and
  27 what the basic operators are.
  28 </p><p>As Kernighan and Ritchie say,
  29 ``The type of an object determines the set of values it can have
  30 and what operations can be performed on it.''
  31 This is a fairly formal, mathematical definition of what a type is,
  32 but it is traditional (and meaningful).
  33 There are several implications to remember:
  34 <OL><li>The ``set of values'' is
  35 finite.
  36 C's <TT>int</TT> type can not represent <em>all</em> of the integers;
  37 its <TT>float</TT> type can not represent <em>all</em>
  38 floating-point numbers.
  39 <li>When you're using an object (that is, a variable) of some type,
  40 you
  41 may
  42 have to remember what values it can take on and what
  43 operations you can perform on it.
  44 For example,
  45 there are several operators which
  46 play with
  47
  48 the binary (bit-level) representation of integers,
  49 but these operators
  50 are not meaningful for
  51 and may not be applied to
  52 floating-point operands.
  53 <li>When declaring a new variable and picking a type for it,
  54 you have to keep in mind the values and operations you'll be needing.
  55 </OL>In other words,
  56 picking a type for a variable is not some abstract academic exercise;
  57 it's closely
  58 connected
  59 to the way(s) you'll be using that variable.
  60 </p><p><a href="sx2a.html" rel=subdocument>2.1 Types</a></p>
  61 <p><a href="sx2b.html" rel=subdocument>2.2 Constants</a></p>
  62 <p><a href="sx2c.html" rel=subdocument>2.3 Declarations</a></p>
  63 <p><a href="sx2d.html" rel=subdocument>2.4 Variable Names</a></p>
  64 <p><a href="sx2e.html" rel=subdocument>2.5 Arithmetic Operators</a></p>
  65 <p><a href="sx2f.html" rel=subdocument>2.6 Assignment Operators</a></p>
  66 <p><a href="sx2g.html" rel=subdocument>2.7 Function Calls</a></p>
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  76 This page by <a href="http://www.eskimo.com/~scs/">Steve Summit</a>
  77 // <a href="copyright.html">Copyright</a> 1995, 1996
  78 // <a href="mailto:scs@eskimo.com">mail feedback</a>
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