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    <p>The code you posted is about half as fast as <code>strcasestr</code>. </p> <pre class="lang-none prettyprint-override"><code>$ gcc -Wall -o my_stristr my_stristr.c steve@solaris:~/code/tmp $ gcc -Wall -o strcasestr strcasestr.c steve@solaris:~/code/tmp $ ./bench ./my_stristr &gt; my_stristr.result ; ./bench ./strcasestr &gt; strcasestr.result; steve@solaris:~/code/tmp $ cat my_stristr.result run 1... time = 6.32 run 2... time = 6.31 run 3... time = 6.31 run 4... time = 6.31 run 5... time = 6.32 run 6... time = 6.31 run 7... time = 6.31 run 8... time = 6.31 run 9... time = 6.31 run 10... time = 6.31 average user time over 10 runs = 6.3120 steve@solaris:~/code/tmp $ cat strcasestr.result run 1... time = 3.82 run 2... time = 3.82 run 3... time = 3.82 run 4... time = 3.82 run 5... time = 3.82 run 6... time = 3.82 run 7... time = 3.82 run 8... time = 3.82 run 9... time = 3.82 run 10... time = 3.82 average user time over 10 runs = 3.8200 steve@solaris:~/code/tmp </code></pre> <p>The <code>main</code> function was: </p> <pre class="lang-c prettyprint-override"><code>int main(void) { char * needle="hello"; char haystack[1024]; int i; for(i=0;i&lt;sizeof(haystack)-strlen(needle)-1;++i) { haystack[i]='A'+i%57; } memcpy(haystack+i,needle, strlen(needle)+1); /*printf("%s\n%d\n", haystack, haystack[strlen(haystack)]);*/ init_stristr(); for (i=0;i&lt;1000000;++i) { /*my_stristr(haystack, needle);*/ strcasestr(haystack,needle); } return 0; } </code></pre> <p>It was suitably modified to test both implementations. I notice as I am typing this up I left in the <code>init_stristr</code> call, but it shouldn't change things too much. <code>bench</code> is just a simple shell script:</p> <pre class="lang-c prettyprint-override"><code>#!/bin/bash function bc_calc() { echo $(echo "scale=4;$1" | bc) } time="/usr/bin/time -p" prog="$1" accum=0 runs=10 for a in $(jot $runs 1 $runs) do echo -n "run $a... " t=$($time $prog 2&gt;&amp;1| grep user | awk '{print $2}') echo "time = $t" accum=$(bc_calc "$accum+$t") done echo -n "average user time over $runs runs = " echo $(bc_calc "$accum/$runs") </code></pre>
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    1. USIharob Al Asimi
    1. USfreespace
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    1. COThank you for the comparison. That's very interesting. My code is from 2003, when strcasstr() did not exist—or at least I didn't know about it (it was added in 2005 according to the glibc CVS history). It seems strcasestr() is not provided by MSVC++, but maybe I can port it from glibc.
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      1. USAnders Sandvig
 

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