PHP中一些有用的函数

<?php/** * 加密解密* * @param string $key* @param string $string* @param string $decrypt* @return string */  function encryptDecrypt($key, $string, $decrypt)
{if($decrypt){$decrypted = rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($key), base64_decode($string), MCRYPT_MODE_CBC, md5(md5($key))), "12");return $decrypted;}else{$encrypted = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($key), $string, MCRYPT_MODE_CBC, md5(md5($key))));return $encrypted;}
}function generateRandomString($length = 10)
{$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';$randomString = '';for ($i = 0; $i < $length; $i++) {$randomString .= $characters[rand(0, strlen($characters) - 1)];}return $randomString;
}/** * 获取扩展名* @param string $filename * @return string */ 
function getExtension($filename)
{$ext = substr($filename, strrpos($filename, '.'));return str_replace('.','',$ext);
}function formatSize($size)
{$sizes = array(" Bytes", " KB", " MB", " GB", " TB", " PB", " EB", " ZB", " YB");if ($size == 0) {  return('n/a');  } else {return (round($size/pow(1024, ($i = floor(log($size, 1024)))), 2) . $sizes[$i]);  }
}function stringParser($string,$replacer)
{$result = str_replace(array_keys($replacer), array_values($replacer),$string);return $result;
}function listDirFiles($DirPath)
{if($dir = opendir($DirPath)){while(($file = readdir($dir))!== false){if(!is_dir($DirPath.$file)) {echo "filename: $file<br />";}}}
}function curPageURL()
{$pageURL = 'http';if (!empty($_SERVER['HTTPS'])) {$pageURL .= "s";}$pageURL .= "://";if ($_SERVER["SERVER_PORT"] != "80") {$pageURL .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];} else {$pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];}return $pageURL;
}function download($filename)
{if ((isset($filename))&&(file_exists($filename))){header("Content-length: ".filesize($filename));header('Content-Type: application/octet-stream');header('Content-Disposition: attachment; filename="' . $filename . '"');readfile("$filename");} else {echo "Looks like file does not exist!";}
}/** * 获取IP地址 * * @return string */ 
function getIp()
{if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown")){$ip = getenv("HTTP_CLIENT_IP");}elseif (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown")){$ip = getenv("HTTP_X_FORWARDED_FOR");}elseif (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown")){$ip = getenv("REMOTE_ADDR");}elseif (isset ($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown")){$ip = $_SERVER['REMOTE_ADDR'];}else$ip = "unknown";return ($ip);
}function injCheck($sql_str)
{  $check = preg_match('/select|insert|update|delete|\'|\/\*|\*|\.\.\/|\.\/|union|into|load_file|outfile/', $sql_str);if ($check) {echo 'Illegal char';exit;} else {return $sql_str;}
}/** * 是否是手机号码 * * @param string $phone 手机号码 * @return boolean */  
function isPhone($phone) {  if (strlen ( $phone ) != 11 || ! preg_match ( '/^1[3|4|5|8][0-9]\d{4,8}$/', $phone )) {  return false;  } else {  return true;  }  
}  
/** * 验证字符串是否为数字,字母,中文和下划线构成 * @param string $username * @return bool */  
function isString($str){  if(preg_match('/^[\x{4e00}-\x{9fa5}\w_]+$/u',$str)){  return true;  }else{  return false;  }  
}  
/** * 是否为一个合法的email * @param sting $email * @return boolean */  
function isEmail($email){  if (filter_var ($email, FILTER_VALIDATE_EMAIL )) {  return true;  } else {  return false;  }  
}  
/** * 是否为一个合法的url * @param string $url * @return boolean */  
function isUrl($url){  if (filter_var ($url, FILTER_VALIDATE_URL )) {  return true;  } else {  return false;  }  
}  
/** * 是否为一个合法的ip地址 * @param string $ip * @return boolean */  
function isIp($ip){  if (ip2long($ip)) {  return true;  } else {  return false;  }  
}  
/** * 是否为整数 * @param int $number * @return boolean */  
function isNnumber($number){  if(preg_match('/^[-\+]?\d+$/',$number)){  return true;  }else{  return false;  }  
}  
/** * 是否为正整数 * @param int $number * @return boolean */  
function isPositiveNumber($number){  if(ctype_digit ($number)){  return true;  }else{  return false;  }  
}  
/** * 是否为小数 * @param float $number * @return boolean */  
function isDecimal($number){  if(preg_match('/^[-\+]?\d+(\.\d+)?$/',$number)){  return true;  }else{  return false;  }  
}  
/** * 是否为正小数 * @param float $number * @return boolean */  
function isPositiveDecimal($number){  if(preg_match('/^\d+(\.\d+)?$/',$number)){  return true;  }else{  return false;  }  
}  
/** * 是否为英文 * @param string $str * @return boolean */  
function isEnglish($str){  if(ctype_alpha($str))  return true;  else  return false;  
}  
/** * 是否为中文 * @param string $str * @return boolean */  
function isChinese($str){  if(preg_match('/^[\x{4e00}-\x{9fa5}]+$/u',$str))  return true;  else   return false;  
}  
/** * 判断是否为图片 * @param string $file  图片文件路径 * @return boolean */  
function isImage($file){  if(file_exists($file) && getimagesize($file===false)){  return false;  }else{  return true;  }  
}  
/** * 是否为合法的身份证(支持15位和18位) * @param string $card * @return boolean */  
function isCard($card){  if(preg_match('/^[1-9]\d{7}((0\d)|(1[0-2]))(([0|1|2]\d)|3[0-1])\d{3}$/',$card) ||preg_match('/^[1-9]\d{5}[1-9]\d{3}((0\d)|(1[0-2]))(([0|1|2]\d)|3[0-1])\d{4}$/',$card))  return true;  else   return false;  
}/** * 验证日期格式是否正确 * @param string $date * @param string $format * @return boolean */  
function isDate($date,$format='Y-m-d'){  $t=date_parse_from_format($format,$date);  if(empty($t['errors'])){  return true;  }else{  return false;  }  
}