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<h1>Idioms</h1>
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Here are some C idioms that may be usefull.
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Place <code>\0</code> at the location pointed to by <code>ptr</code>
then increment <code>ptr</code>
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*ptr++ = '\0';
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Increment <code>ptr</code> then
place <code>\0</code> at the location pointed to by <code>ptr</code>
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*++ptr = '\0';
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This program will print its self! I guess its not of any real
use, but I think its clever.
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main(a) {a="main(a) {a=%c%s%c;printf(a,34,a,34);}";printf(a,34,a,34);}
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This is something I saw out on the web. It swaps the value of two
variables without
using a third variable as a temporary store.
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one ^= two;
two ^= one;
one ^= two;
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Have you ever had a SEGV from <a href="../FUNCTIONS/printf.html">printf</a>
because you passed a NULL pointer to a %s flag???. This idiom will put
a stop to all that nonsence.
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printf("%s\n", Str ? Str : "Null");
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<img src="../../GRAPHICS/computer.gif" alt="o">
<a href=../EXAMPLES/swap.c>Program swapping the contents of two variables</a>.
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<h2>See Also:</h2>
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<a href="got_ya.html">Common Coding Errors</a>.<p>
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<address>Martin Leslie
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?id=0e1929dedea36781e25902118c93edd8d8f09af1'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools?id=0e1929dedea36781e25902118c93edd8d8f09af1'>tools</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/testing?id=0e1929dedea36781e25902118c93edd8d8f09af1'>testing</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/testing/selftests?id=0e1929dedea36781e25902118c93edd8d8f09af1'>selftests</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/testing/selftests/ftrace?id=0e1929dedea36781e25902118c93edd8d8f09af1'>ftrace</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/testing/selftests/ftrace/test.d?id=0e1929dedea36781e25902118c93edd8d8f09af1'>test.d</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/testing/selftests/ftrace/test.d/functions?id=0e1929dedea36781e25902118c93edd8d8f09af1'>functions</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='0e1929dedea36781e25902118c93edd8d8f09af1'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Mike Looijmans <mike.looijmans@topic.nl></td><td class='right'>2017-01-16 15:49:38 +0100</td></tr>
<tr><th>committer</th><td>Wolfram Sang <wsa@the-dreams.de></td><td class='right'>2017-01-25 22:07:40 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/testing/selftests/ftrace/test.d/functions?id=0e1929dedea36781e25902118c93edd8d8f09af1'>0e1929dedea36781e25902118c93edd8d8f09af1</a> (<a href='/cgit.cgi/linux/net-next.git/patch/tools/testing/selftests/ftrace/test.d/functions?id=0e1929dedea36781e25902118c93edd8d8f09af1'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=0e1929dedea36781e25902118c93edd8d8f09af1'>5e353f42c88f892c20528b8a4c28856919594944</a> /<a href='/cgit.cgi/linux/net-next.git/tree/tools/testing/selftests/ftrace/test.d/functions?id=0e1929dedea36781e25902118c93edd8d8f09af1'>tools/testing/selftests/ftrace/test.d/functions</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/testing/selftests/ftrace/test.d/functions?id=7a308bb3016f57e5be11a677d15b821536419d36'>7a308bb3016f57e5be11a677d15b821536419d36</a> (<a href='/cgit.cgi/linux/net-next.git/diff/tools/testing/selftests/ftrace/test.d/functions?id=0e1929dedea36781e25902118c93edd8d8f09af1&id2=7a308bb3016f57e5be11a677d15b821536419d36'>diff</a>)</td></tr></table>
<div class='commit-subject'>i2c: i2c-cadence: Initialize configuration before probing devices</div><div class='commit-msg'>The cadence I2C driver calls cdns_i2c_writereg(..) to setup a workaround
in the controller, but did so after calling i2c_add_adapter() which starts
probing devices on the bus. Change the order so that the configuration is
completely finished before using the adapter.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=0e1929dedea36781e25902118c93edd8d8f09af1'>Diffstat</a> (limited to 'tools/testing/selftests/ftrace/test.d/functions')</div><table summary='diffstat' class='diffstat'>