?

<?php
/**
 * 获得用户操作系统的换行符 
 *
 * @access  public 
 * @return  string 
 */  
function get_crlf()
{
	/* LF (Line Feed, 0x0A, \N) 和 CR(Carriage Return, 0x0D, \R) */
	if (stristr($_SERVER['HTTP_USER_AGENT'], 'Win')){
		$the_crlf = '\r\n';
	}elseif (stristr($_SERVER['HTTP_USER_AGENT'], 'Mac')){
		$the_crlf = '\r'; // for old MAC OS
	}else{
		$the_crlf = '\n';
	}

	return $the_crlf;
}
// *nix
echo DIRECTORY_SEPARATOR; // /
echo PHP_SHLIB_SUFFIX;    // so
echo PATH_SEPARATOR;      // :

// Win*
echo DIRECTORY_SEPARATOR; // \
echo PHP_SHLIB_SUFFIX;    // dll
echo PATH_SEPARATOR;      // ;
?> 
?

if ?( strtoupper ( substr (PHP_OS,?0,?3))?===? 'WIN' )?{? ?? 得到操作系统类型

DEFAULT_INCLUDE_PATH? 得到php.ini中配置的include_path