Threads in the new ISO C Standard from 2011
Threads in the new ISO C Standard from 2011
Threads in the new ISO C Standard from 2011
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Sequenced Before<br />
The most common sequence po<strong>in</strong>t <strong>in</strong> C/C++ is semicolon.<br />
O<strong>the</strong>rs <strong>in</strong>clude:<br />
Function call<br />
Comma operator<br />
After evaluat<strong>in</strong>g <strong>the</strong> left operand of ?:, && and ||.<br />
Below at L, <strong>the</strong> assignment to and use of v not sequenced.<br />
<strong>in</strong>t u = 1, v = 2, w;<br />
L: w = (v = u + 3) + v * 4;<br />
It is legal C but <strong>the</strong> value of w can become ei<strong>the</strong>r 12 or 20.<br />
It is due to it is unspecified which operand of + is evaluated first.<br />
In <strong>the</strong> follow<strong>in</strong>g w becomes 20 s<strong>in</strong>ce comma is a sequence po<strong>in</strong>t.<br />
w = (v = u + 3), v * 4;<br />
Jonas Skeppstedt (js@cs.lth.se) Lecture 6 2013 27 / 70
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