Inspired by https://gist.github.com/loganlinn/2165297, I want to see just `strtolower()` in an if though, and I wanted to see the results for larger values of `n`

Results.txt

mstemle@mstemle901:~/Desktop$ ./runtests.sh
String length: 512
************************
* if + strtolower *
************************
Time: 0.001159
Memory: 1904
************************
*      strcasecmp      *
************************
Memory: 1888
Time: 0.000869


String length: 1024
************************
* if + strtolower *
************************
Time: 0.004334
Memory: 2928
************************
*      strcasecmp      *
************************
Memory: 2912
Time: 0.001288


String length: 2048
************************
* if + strtolower *
************************
Time: 0.012139
Memory: 4976
************************
*      strcasecmp      *
************************
Memory: 4960
Time: 0.003871


String length: 32768
************************
* if + strtolower *
************************
Time: 2.708231
Memory: 66416
************************
*      strcasecmp      *
************************
Memory: 66400
Time: 0.384644

runtests.sh

STRTOLOWER="./strtolower_test.php"
STRCASECMP="./strcasecmp_test.php"

SIZES=(
    $(expr 1 \* 512)          # 1/2 KB
    $(expr 1 \* 1024)         # 1   KB
    $(expr 1 \* 1024 \* 2)    # 2   KB
    $(expr 1 \* 1024 \* 32)   # 32  KB
)

for i in "${SIZES[@]}"; do
    echo "String length: $i"
    $STRTOLOWER "$i"
    $STRCASECMP "$i"
    echo -e "\n"
done

strcasecmp_test.php

#!/usr/bin/env php
<?php
$n = isset($argv[1]) ? (int) $argv[1] : 200;
$before = memory_get_usage();
$start = microtime(true);
$a = '';
$b = '';
for ($i = 0; $i < $n; $i++) {
    $a .= $i % 2 ? "A" : 'a';
    $b .= 'a';
    if ( 0 == strcasecmp($a, $b) )
    {
        // Do nothing
    }
}
$end = microtime(true);
$after = memory_get_usage();
printf("************************\n");
printf("*      strcasecmp      *\n");
printf("************************\n");
printf("Memory: %d\n", $after - $before);
printf("Time: %f\n", $end - $start);

strtolower_test.php

#!/usr/bin/env php
<?php
$n = isset($argv[1]) ? (int) $argv[1] : 200;
$before = memory_get_usage();
$start = microtime(true);
$a = '';
$b = '';
for ($i = 0; $i < $n; $i++) {
    $a .= $i % 2 ? "A" : 'a';
    $b .= 'a';
    if ( strtolower($a) == $b ) {
        // Do nothing
    }
}
$end = microtime(true);
$after = memory_get_usage();
printf("************************\n");
printf("* if + strtolower *\n");
printf("************************\n");
printf("Time: %f\n", $end - $start);
printf("Memory: %d\n", $after - $before);