A collection of some common functions in php_PHP tutorial

/*获得客户端ip地址*/
    function getIP() {
        if(getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"),"unknown")) {
                $ip = getenv("HTTP_CLIENT_IP");
        }
        else if(getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"),"unknown")) {
                $ip = getenv("HTTP_X_FORWARDED_FOR");
        }
        else if(getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"),"unknown")) {
                $ip = getenv("REMOTE_ADDR");
        }
        else if(isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'],"unknown")) {
                $ip = $_SERVER['REMOTE_ADDR'];
        }
        else {
                $ip = "unknown";
        }

        return($ip);
}

/*验证IP地址函数*/
function checkIP($ip) {
        return preg_match((2[0-4]d|25[0-5]|[01]?dd?).){3}(2[0-4]d|25[0-5]|[01]?dd?);
}

/*用户输入内容过滤函数*/
function getStr($str) {
    $tmpstr = trim($str);
    $tmpstr = strip_tags($tmpstr);
    $tmpstr = htmlspecialchars($tmpstr);

    /*加入字符转义*/
    $tmpstr = addslashes($tmpstr);

    return $tmpstr;
}

/*容量大小计算函数*/
function sizecount($filesize) {
        if($filesize >= 1073741824) {
                $filesize = round($filesize / 1073741824 * 100) / 100 . ' G';
        } elseif($filesize >= 1048576) {
                $filesize = round($filesize / 1048576 * 100) / 100 . ' M';
        } elseif($filesize >= 1024) {
                $filesize = round($filesize / 1024 * 100) / 100 . ' K';
        } else {
                $filesize = $filesize . ' bytes';
        }
        return $filesize;
}

/*简单防SQL注入函数*/
function getSQL($feild) {
    $tmpfeild = mysql_escape_string($feild);

    return $tmpfeild;
}
/*$num必须为英文字符或数字0-9*/
function getNums($num) {
    return (ctype_alnum($num));
}

/*$char必须为英文字符*/
function getChar($char) {
    return (ctype_alpha($char));
}
/*匹配qq(5-12)位*/
function getQQ($qq) {
    return preg_match("/^b[0-9]{5,12}b/",$qq);
}
/*匹配电子邮件地址*/
function getEmail($email) {
    return strlen($email)>6 && preg_match("/^w+@(w+.)+[com]|[cn]$/" , $email);
// preg_match("/^[w-.]+@[w-.]+(.w+)+$/",$email);
}

/*Generate email connection*/
function emailconv($email,$tolink=1) {
         $email=str_replace(array('@','.'),array(' @','.'),$email);
return $tolink ? ''.$email.'': $ Email;
}

/*Check whether the IP is allowed to access*/
Function iPaccess ($ IP, $ Accesslist) {
Return Preg_match ("/^(" (". Str_replace ( array("rn",' '),array('|',''),preg_quote($accesslist,'/')).")/",$ip);
}

/*If the title is too long, this function can display the first few characters and replace the remaining characters with...*/
function cutstr($string, $length) {
if(strlen($string) > $length) {
for($i = 0; $i < $length - 3; $i++) {
/*Returns the ordinal value of the character*/
$strcut .= ord($string [$i]) > 127 ? $string[$i].$string[++$i] : $string[$i]; 🎜> } else {
return $string;
}
}