本篇文章是对一些php项目中比较通用的php自建函数进行了详细的分析介绍，需要的朋友参考下

以下一些php函数是我们it动力最常用的项目开发函数，这些函数还算是在比较多的项目中使用到的，也是比较通用的。
1.请求接口的处理函数

/** 
 * curl访问程序接口 
 * @param string 
 * @return array 
 */  
function getCurlDate($url, $datas, $key) {  
    $datas['time'] = $_SERVER['REQUEST_TIME'] + 300;  
    $post_data['post'] = urlencode(authcode(serialize($datas), "ENCODE", $key));  
//    echo $url;  
    $ch = curl_init();  
    curl_setopt($ch, CURLOPT_URL, $url);  
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);  
    // 我们在POST数据哦！  
    curl_setopt($ch, CURLOPT_POST, 1);  
    // 把post的变量加上  
    curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);  
    $output = curl_exec($ch);  
 //   dump(curl_error($ch));  
    curl_close($ch);  
    return json_decode($output, true);  
}  

2.获取文件扩展名

/** 
 * @获取文件扩展名 
 * @$pic string 图片路径 
 */  
function get_file_ext($pic) {  
    return substr($pic, strrpos($pic, '.') + 1);  
}  

3.可逆的加密、解密函数

/** 
 * 字符串加密 
 * @param   $string     需加密的字符 
 * @param   $operation  加密或解密 
 * @param   $key        网站加密key，防止破解 
 * @return  string 
 */  
function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0) {  
    $ckey_length = 4;  
    $key = md5($key ? $key : '^www.itokit.com$');  
    $keya = md5(substr($key, 0, 16));  
    $keyb = md5(substr($key, 16, 16));  
    $keyc = $ckey_length ? ($operation == 'DECODE' ? substr($string, 0, $ckey_length) : substr(md5(microtime()), -$ckey_length)) : '';  

    $cryptkey = $keya . md5($keya . $keyc);  
    $key_length = strlen($cryptkey);  

    $string = $operation == 'DECODE' ? base64_decode(substr($string, $ckey_length)) : sprintf('%010d', $expiry ? $expiry + time() : 0) . substr(md5($string . $keyb), 0, 16) . $string;  
    $string_length = strlen($string);  

    $result = '';  
    $box = range(0, 255);  

    $rndkey = array();  
    for ($i = 0; $i <= 255; $i++) {  
        $rndkey[$i] = ord($cryptkey[$i % $key_length]);  
    }  

    for ($j = $i = 0; $i < 256; $i++) {  
        $j = ($j + $box[$i] + $rndkey[$i]) % 256;  
        $tmp = $box[$i];  
        $box[$i] = $box[$j];  
        $box[$j] = $tmp;  
    }  

    for ($a = $j = $i = 0; $i < $string_length; $i++) {  
        $a = ($a + 1) % 256;  
        $j = ($j + $box[$a]) % 256;  
        $tmp = $box[$a];  
        $box[$a] = $box[$j];  
        $box[$j] = $tmp;  
        $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));  
    }  

    if ($operation == 'DECODE') {  
        if ((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26) . $keyb), 0, 16)) {  
            return substr($result, 26);  
        } else {  
            return '';  
        }  
    } else {  
        return $keyc . str_replace('=', '', base64_encode($result));  
    }  
}  

4.字符串转十六进制

/** 
* 字符串转十六进制 
* @param unknown_type $s 
*/  
function str2hex($s) {  
  $r = "";  
  $hexes = array ("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f");  
  for ($i=0; $i<strlen($s); $i++)  
  $r .= ($hexes [(ord($s{$i}) >> 4)] . $hexes [(ord($s{$i}) & 0xf)]);  
  return $r;  
} 

5.十六进制转字符串

/** 
* 十六进制转字符串 
* @param unknown_type $s 
*/  
function hex2str($s) {  
  $r = "";  
  for ( $i = 0; $i<strlen($s); $i += 2)  
  {  
    $x1 = ord($s{$i});  
    $x1 = ($x1>=48 && $x1<58) ? $x1-48 : $x1-97+10;  
    $x2 = ord($s{$i+1});  
    $x2 = ($x2>=48 && $x2<58) ? $x2-48 : $x2-97+10;  
    $r .= chr((($x1 << 4) & 0xf0) | ($x2 & 0x0f));  
  }  
  return $r;  
}  

6.返回经addslashes处理过的字符串或数组

/** 
* 返回经addslashes处理过的字符串或数组 
* @param $string 需要处理的字符串或数组 
* @return mixed 
*/  
function new_addslashes($string){  
  if(!is_array($string)) return addslashes($string);  
  foreach($string as $key => $val) $string[$key] = new_addslashes($val);  
  return $string;  
}  

/**/  
function addslashes_deep($string)  
{  
  return is_array($string) ? array_map('addslashes_deep', $string) : addslashes($string);  
}  

7.返回经stripslashes处理过的字符串或数组

/** 
* 返回经stripslashes处理过的字符串或数组 
* @param $string 需要处理的字符串或数组 
* @return mixed 
*/  
function new_stripslashes($string) {  
  if(!is_array($string)) return stripslashes($string);  
  foreach($string as $key => $val) $string[$key] = new_stripslashes($val);  
  return $string;  
}  
/**/  
function stripslashes_deep($string)  
{  
  return is_array($string) ? array_map('stripslashes_deep', $string) : stripslashes($string);  
}  

8.返回经 htmlspecialchars 处理过的字符串或数组

/** 
* 返回经 htmlspecialchars 处理过的字符串或数组 
* @param $string 需要处理的字符串或数组 
* @return mixed 
*/  
function new_html_special_chars($string) {  
  if(!is_array($string)) return htmlspecialchars($string);  
  foreach($string as $key => $val) $string[$key] = new_html_special_chars($val);  
  return $string;  
}  

9.获取请求ip

/** 
 * 获取请求ip 
 * 
 * @return ip地址 
 */  
function ip() {  
  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'];  
  }  
  return preg_match ( '/[\d\.]{7,15}/', $ip, $matches ) ? $matches [0] : '';  
}  

10.字符截取 支持UTF8/GBK

/** 
* 字符截取 支持UTF8/GBK 
* @param $string 
* @param $length 
* @param $dot 
*/  
function str_cut($string, $length, $dot = '...') {  
  $strlen = strlen($string);  
  if($strlen <= $length) return $string;  
  $string = str_replace(array(' ',' ', '&', '"', ''', '“', '”', '―', '<', '>', '・', '…'), array('∵',' ', '&', '"', "'", '“', '”', '―', '<', '>', '・', '…'), $string);  
  $strcut = '';  
  if(strtolower(CHARSET) == 'utf-8') {  
    $length = intval($length-strlen($dot)-$length/3);  
    $n = $tn = $noc = 0;  
    while($n < strlen($string)) {  
      $t = ord($string[$n]);  
      if($t == 9 || $t == 10 || (32 <= $t && $t <= 126)) {  
        $tn = 1; $n++; $noc++;  
      } elseif(194 <= $t && $t <= 223) {  
        $tn = 2; $n += 2; $noc += 2;  
      } elseif(224 <= $t && $t <= 239) {  
        $tn = 3; $n += 3; $noc += 2;  
      } elseif(240 <= $t && $t <= 247) {  
        $tn = 4; $n += 4; $noc += 2;  
      } elseif(248 <= $t && $t <= 251) {  
        $tn = 5; $n += 5; $noc += 2;  
      } elseif($t == 252 || $t == 253) {  
        $tn = 6; $n += 6; $noc += 2;  
      } else {  
        $n++;  
      }  
      if($noc >= $length) {  
        break;  
      }  
    }  
    if($noc > $length) {  
      $n -= $tn;  
    }  
    $strcut = substr($string, 0, $n);  
    $strcut = str_replace(array('∵', '&', '"', "'", '“', '”', '―', '<', '>', '・', '…'), array(' ', '&', '"', ''', '“', '”', '―', '<', '>', '・', '…'), $strcut);  
  } else {  
    $dotlen = strlen($dot);  
    $maxi = $length - $dotlen - 1;  
    $current_str = '';  
    $search_arr = array('&',' ', '"', "'", '“', '”', '―', '<', '>', '・', '…','∵'); 
    $replace_arr = array('&',' ', '"', ''', '“', '”', '―', '<', '>', '・', '…',' ');  
    $search_flip = array_flip($search_arr);  
    for ($i = 0; $i < $maxi; $i++) {  
      $current_str = ord($string[$i]) > 127 ? $string[$i].$string[++$i] : $string[$i];  
      if (in_array($current_str, $search_arr)) {  
        $key = $search_flip[$current_str];  
        $current_str = str_replace($search_arr[$key], $replace_arr[$key], $current_str);  
      }  
      $strcut .= $current_str;  
    }  
  }  
  return $strcut.$dot;  
}  

11.产生随机字符串

/** 
* 产生随机字符串 
* 
* @param        int                $length    输出长度  
* @param        string         $chars     可选的 ，默认为 0123456789 
* @return     string         字符串 
*/  
function random($length, $chars = '0123456789') {  
  $hash = '';  
  $max = strlen($chars) - 1;  
  for($i = 0; $i < $length; $i++) {  
    $hash .= $chars[mt_rand(0, $max)];  
  }  
  return $hash;  
}  

12.将字符串转换为数组

/** 
* 将字符串转换为数组 
* 
* @param  string  $data  字符串 
* @return  array  返回数组格式，如果，data为空，则返回空数组 
*/  
function string2array($data) {  
  if($data == '') return array();  
  eval("\$array = $data;");  
  return $array;  
}  

13.将数组转换为字符串

/** 
* 将数组转换为字符串 
* 
* @param  array  $data    数组 
* @param  bool  $isformdata  如果为0，则不使用new_stripslashes处理，可选参数，默认为1 
* @return  string  返回字符串，如果，data为空，则返回空 
*/  
function array2string($data, $isformdata = 1) {  
  if($data == '') return '';  
  if($isformdata) $data = new_stripslashes($data);  
  return addslashes(var_export($data, TRUE));  
}  

14.转换字节数为其他单位

/** 
* 转换字节数为其他单位 
* 
* 
* @param        string        $filesize        字节大小 
* @return        string        返回大小 
*/  
function sizecount($filesize) {  
        if ($filesize >= 1073741824) {  
                $filesize = round($filesize / 1073741824 * 100) / 100 .' GB';  
        } elseif ($filesize >= 1048576) {  
                $filesize = round($filesize / 1048576 * 100) / 100 .' MB';  
        } elseif($filesize >= 1024) {  
                $filesize = round($filesize / 1024 * 100) / 100 . ' KB';  
        } else {  
                $filesize = $filesize.' Bytes';  
        }  
        return $filesize;  
}