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