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76 lines
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Next: <a rel="next" accesskey="n" href="M2-Checks.html#M2-Checks">M2 Checks</a>,
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<h5 class="subsubsection">15.4.9.6 Deviations from Standard Modula-2</h5>
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<p><a name="index-Modula_002d2_002c-deviations-from-1049"></a>
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A few changes have been made to make Modula-2 programs easier to debug.
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This is done primarily via loosening its type strictness:
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<ul>
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<li>Unlike in standard Modula-2, pointer constants can be formed by
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integers. This allows you to modify pointer variables during
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debugging. (In standard Modula-2, the actual address contained in a
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pointer variable is hidden from you; it can only be modified
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through direct assignment to another pointer variable or expression that
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returned a pointer.)
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<li>C escape sequences can be used in strings and characters to represent
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non-printable characters. <span class="sc">gdb</span> prints out strings with these
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escape sequences embedded. Single non-printable characters are
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printed using the ‘<samp><span class="samp">CHR(</span><var>nnn</var><span class="samp">)</span></samp>’ format.
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<li>The assignment operator (<code>:=</code>) returns the value of its right-hand
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argument.
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<li>All built-in procedures both modify <em>and</em> return their argument.
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</ul>
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