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run code in 150+ php & hhvm versions
Bugs & Features
<?php /** strrev function implementation taken from ext/standard/string.c PHP-5-5 branch http://lxr.php.net/xref/PHP_5_5/ext/standard/string.c#3165 // {{{ proto string strrev(string str) // Reverse a string PHP_FUNCTION(strrev) { char *str; char *e, *n, *p; int str_len; if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &str, &str_len) == FAILURE) { return; } n = emalloc(str_len+1); p = n; e = str + str_len; while (--e>=str) { *p++ = *e; } *p = '\0'; RETVAL_STRINGL(n, str_len, 0); } // }}} */ // PHP Implementation function userland_strrev($string) { if (!is_string($string)) { return false; } $new_string = ""; $len = strlen($string); while (--$len) { $new_string .= $string[$len]; } return $new_string; } $string = "Hello PHP!"; var_dump(strrev($string), userland_strrev($string)); /* for ($i = 0; $i < $n; $i++) { $t = microtime(true); $php[] = microtime(true) - $t; } */
Output for 4.3.0 - 5.6.28, hhvm-3.10.0 - 3.12.0, 7.0.0 - 7.1.0
string(10) "!PHP olleH" string(9) "!PHP olle"