mingw/info/gdb/Deviations.html

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  12 Node:<a name="Deviations">Deviations</a>,
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  18
  19 <h5 class="subsubsection">Deviations from standard Modula-2</h5>
  20
  21    <p>A few changes have been made to make Modula-2 programs easier to debug.
  22 This is done primarily via loosening its type strictness:
  23
  24      <ul>
  25 <li>Unlike in standard Modula-2, pointer constants can be formed by
  26 integers.  This allows you to modify pointer variables during
  27 debugging.  (In standard Modula-2, the actual address contained in a
  28 pointer variable is hidden from you; it can only be modified
  29 through direct assignment to another pointer variable or expression that
  30 returned a pointer.)
  31
  32      <li>C escape sequences can be used in strings and characters to represent
  33 non-printable characters.  GDB prints out strings with these
  34 escape sequences embedded.  Single non-printable characters are
  35 printed using the <code>CHR(</code><var>nnn</var><code>)</code> format.
  36
  37      <li>The assignment operator (<code>:=</code>) returns the value of its right-hand
  38 argument.
  39
  40      <li>All built-in procedures both modify <em>and</em> return their argument.
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