Undefined values: Difference between revisions
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→{{header|Phix}}: added syntax colouring the hard way, phix/basics
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=={{header|Phix}}==
{{libheader|Phix/basics}}
Phix has a special unassigned value, that can be tested for using object(). (There is no offical way to "un-assign" a variable, though you could fairly easily do so with a bit of inline assembly.)
<!--<lang Phix>
<span style="color: #004080;">object</span> <span style="color: #000000;">x</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">test</span><span style="color: #0000FF;">()</span>
<span style="color: #008080;">if</span> <span style="color: #004080;">object</span><span style="color: #0000FF;">(</span><span style="color: #000000;">x</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"x is an object\n"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">else</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"x is unassigned\n"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #000000;">test</span><span style="color: #0000FF;">()</span>
<span style="color: #000000;">x</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
test()</lang>▼
<span style="color: #000000;">test</span><span style="color: #0000FF;">()</span>
{{out}}
<pre>
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