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   9 <title>Chapter 7: Input and Output</title>
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  15 <H1>Chapter 7: Input and Output</H1>
  16
  17 <p>page 151
  18 </p><p>By ``Input and output facilities are
  19 not part of the C language itself,''
  20 we
  21 mean that things like <TT>printf</TT> are just
  22 function calls like any other.
  23 C has
  24 no built-in input or output statements.
  25 For our purposes,
  26 the implications of this
  27 fact--that I/O is not built in--is
  28 mainly that the compiler may not do as much checking
  29 as we might like it to.
  30 If we accidentally write
  31 <pre>   double d = 1.23;
  32         printf("%d\n", d);
  33 </pre>the compiler says,
  34 ``Hmm, a function named <TT>printf</TT>
  35 is being called with a string and a <TT>double</TT>.
  36 Okay by me.''
  37 The compiler does not
  38 (and, in general, could not even if it wanted to)
  39 notice that the <TT>%d</TT> format requires an <TT>int</TT>.
  40 </p><p>Although the title of this chapter is ``Input and Output,''
  41 it appears that we'll also be meeting
  42 a few other routines from the standard library.
  43 </p><p>If you start to do any serious programming on a particular system,
  44 you'll undoubtedly discover that it has a number of more
  45 specialized input/output
  46 (and other system-related) routines available,
  47 which promise better performance or nicer functionality
  48 than
  49 the pedestrian routines of C's standard library.
  50 You should resist the temptation to use these nonstandard routines.
  51 Because the standard library routines are defined precisely and
  52 ``exist in compatible form on any system where C exists,''
  53 there are some real advantages to using them.
  54 (On the other hand,
  55 when you need to do something
  56 which C's standard library routines don't provide,
  57 you'll generally turn
  58 to your machine's system-specific routines right away,
  59 as they may be your only choice.
  60 One common example is when
  61 you'd like to read one character immediately,
  62 without waiting for the RETURN key.
  63 How you do that depends on what system you're using;
  64 it is not defined by C.)
  65 </p><p><a href="sx10a.html" rel=subdocument>section 7.1: Standard Input and Output</a></p>
  66 <p><a href="sx10b.html" rel=subdocument>section 7.2: Formatted Output--Printf</a></p>
  67 <p><a href="sx10c.html" rel=subdocument>section 7.3: Variable-length Argument Lists</a></p>
  68 <p><a href="sx10d.html" rel=subdocument>section 7.4: Formatted Input--Scanf</a></p>
  69 <p><a href="sx10e.html" rel=subdocument>section 7.5: File Access</a></p>
  70 <p><a href="sx10f.html" rel=subdocument>section 7.6: Error Handling--Stderr and Exit</a></p>
  71 <p><a href="sx10g.html" rel=subdocument>section 7.7: Line Input and Output</a></p>
  72 <p><a href="sx10h.html" rel=subdocument>section 7.8.1: String Operations</a></p>
  73 <p><a href="sx10i.html" rel=subdocument>section 7.8.2: Character Class Testing and Conversion</a></p>
  74 <p><a href="sx10j.html" rel=subdocument>section 7.8.3: Ungetc</a></p>
  75 <p><a href="sx10k.html" rel=subdocument>section 7.8.4: Command Execution</a></p>
  76 <p><a href="sx10l.html" rel=subdocument>section 7.8.5: Storage Management</a></p>
  77 <p><a href="sx10m.html" rel=subdocument>section 7.8.6: Mathematical Functions</a></p>
  78 <p><a href="sx10n.html" rel=subdocument>section 7.8.7: Random Number Generation</a></p>
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  88 This page by <a href="http://www.eskimo.com/~scs/">Steve Summit</a>
  89 // <a href="copyright.html">Copyright</a> 1995, 1996
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