【编者按】网学网PHP频道为大家收集整理了“PHP项目开发中最常用的自定义函数整理“提供大家参考，希望对大家有所帮助!

<?php
//alert提示
function alert($msg){
echo "<script>alert(''$msg'');</script>";
}
//把一些预定义的字符转换为 HTML 实体
function d_htmlspecialchars($string) {
if(is_array($string)) {
foreach($string as $key => $val) {
$string[$key] = d_htmlspecialchars($val);
}
} else {
$string = str_replace(''&'', ''&'', $string);
$string = str_replace(''"'', ''"'', $string);
$string = str_replace('''''', ''''', $string);
$string = str_replace(''<'', ''<'', $string);
$string = str_replace(''>'', ''>'', $string);
$string = preg_replace(''/&(#\d;)/'', ''&\1'', $string);
}
return $string;
}
//在预定义字符前加上反斜杠，包括 单引号、双引号、反斜杠、NULL，以保护数据库安全
function d_addslashes($string, $force = 0) {
if(!$GLOBALS[''magic_quotes_gpc''] || $force) {
if(is_array($string)) {
foreach($string as $key => $val) $string[$key] = d_addslashes($val, $force);
}
else $string = addslashes($string);
}
return $string;
}
//生成随机字符串，包含大写、小写字母、数字
function randstr($length) {
$hash = '''';
$chars = ''ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz'';
$max = strlen($chars) - 1;
mt_srand((double)microtime() * 1000000);
for($i = 0; $i < $length; $i++) {
$hash .= $chars[mt_rand(0, $max)];
}
return $hash;
}
//转换时间戳为常用的日期格式
function trans_time($timestamp){
if($timestamp < 1) echo ''无效的Unix时间戳'';
else return date("Y-m-d H:i:s",$timestamp);
}
//获取IP
function get_ip() {
if ( SERVER["HTTP_X_FORWARDED_FOR"])
$ip = SERVER["HTTP_X_FORWARDED_FOR"];
else if ( SERVER["HTTP_CLIENT_IP"])
$ip = SERVER["HTTP_CLIENT_IP"];
else if ( SERVER["REMOTE_ADDR"])
$ip = SERVER["REMOTE_ADDR"];
else if (getenv("HTTP_X_FORWARDED_FOR"))
$ip = getenv("HTTP_X_FORWARDED_FOR");
else if (getenv("HTTP_CLIENT_IP"))
$ip = getenv("HTTP_CLIENT_IP");
else if (getenv("REMOTE_ADDR"))
$ip = getenv("REMOTE_ADDR");
else
$ip = "Unknown";
return $ip;
}
//计算时间差：默认返回类型为“分钟”
//$old_time 只能是时间戳，$return_type 为 h 是小时，为 s 是秒
function timelag($old_time,$return_type=''m''){
if($old_time < 1){
echo ''无效的Unix时间戳'';
}else{
switch($return_type){
case ''h'':
$type = 3600; break;
case ''m'':
$type = 60; break;
case ''s'':
$type = 1; break;
case '''':
$type = 60; break;
}
$dif = round( (time()-$old_time)/$type ) ;
return $dif;
}
}
//获取当前页面的URL地址
function url_this(){
$url = "http://". SERVER ["HTTP_HOST"]. SERVER["REQUEST_URI"];
$return_url = "<a href=''$url''>$url</a>";
return $return_url;
}
//跳转函数
function url_redirect($url,$delay=''''){
if($delay == ''''){
echo "<script>window.location.href=''$url''</script>";
}else{
echo "<meta http-equiv=''refresh'' content=''$delay;URL=$url'' />";
}
}
} //end func

?>