PHP自定义函数+系统函数库
全局变量
$n = 5; //全局变量
function fun1(){
global $n;
echo ‘我在函数体内也可以调用全局变量n,它的值是:‘ , $n;//5
$n++;
}
fun1();
echo ‘<hr>‘;
echo $n;//6$n = 6;
function fun1(){
echo ‘变量的值是:‘ , $GLOBALS[‘n‘];
$GLOBALS[‘n‘]++;
}
fun1();
echo $GLOBALS[‘n‘];不使用循环语句，来计算1~100的和
function recursive($n){
if($n>=1){
return $n + recursive($n-1);
}
}
echo recursive(100);引用
$foo = ‘Bob‘;
$bar = &$foo; //看待成变量的别名
$bar = ‘Rose‘;
echo $foo;//Rose
$foo = ‘Mooc‘;
$bar = &$foo; //看待成变量的别名
unset($foo); //变量销毁
echo $bar;//Mooc自定义函数
function fun1(&$n){
$n++;
echo ‘我是函数体内的局部变量‘ , $n ;//4
}
$n = 3;
fun1($n);
echo $n , ‘<hr>‘;//4获得扩展名
function getExtension($filename)
{
$pos = strrpos($filename, ‘.‘);
$extension = strtolower(substr($filename, $pos + 1));
return $extension;
}
$path = ‘mooc.func.pHP‘;
var_dump(getExtension($path));求平均数
function avg(...$args)
{
return $args;
}
var_dump(avg(1, 2, 3));系统函数库
字符串转数组
$str = ‘A|B|C|D‘;
$arr = explode(‘|‘, $str);
print_r($arr);//[A,B,C,D]数组转字符串
$arr2 = array(‘Tom‘,‘John‘,‘Rose‘);
$str2 = implode(‘,‘,$arr2);
echo $str2;//Tom,John,Rose获取扩展名：
方法一
$filename = ‘ab.cd.gif.JpEg‘; //gepj.fig.dc.ba
$num = strrpos($filename, ‘.‘);
echo strtolower(substr($filename, $num+1)) , ‘<br/><br/>‘;//jpeg方法二
$filename = ‘ab.cd.gif.JpEg‘; //gepj.fig.dc.ba
$str2 = strrev($filename);//strrev反转字符串
$num = strpos($str2, ‘.‘);
echo strtolower(strrev(substr($str2, 0,$num)));//jpegtrim移除字符串两侧的字符
$str = "\n\n\t\tABC\t\t";
echo trim($str);//ABCmd5()加密
$str = ‘abc‘;
echo md5($str);//900150983cd24fb0d6963f7d28e17f72格式化字符串
$number = 5;
$str = ‘shanghai‘;
$txt = sprintf(‘there are %d million cars in %s‘,$number,$str);
echo $txt;//there are 5 million cars in shanghai
$number = 123;
$txt = sprintf("带有两位小数的结果是:%1\$.2f,\n不带小数的是:%1\$d",$number);
echo $txt;//带有两位小数的结果是:123.00,不带小数的是:123htmlspecialchars特殊字符转为HTML实体
$str = "A>B,B<C,Tom&John,He said:\"I‘m OK\"";
echo htmlspecialchars($str,ENT_QUOTES);//A>B,B<C,Tom&John,He said:"I'm OK"通过str_replace进行转换
$str1 = str_replace(‘&‘, ‘&‘, $str); //必须是第一阶梯
$str2 = str_replace(‘>‘, ‘>‘, $str1);
$str2 = str_replace(‘<‘, ‘<‘, $str2);
$str2 = str_replace(‘"‘, ‘"‘, $str2);
$str2 = str_replace(‘\‘‘, ‘'‘, $str2);
echo $str2;//A>B,B<C,Tom&John,He said:"I'm OK"str_ireplace不区分大小写
$str = ‘javascript‘;
echo str_ireplace(‘A‘, ‘b‘, $str);//jbvbscript随机地打乱字符串中的所有字符
$str = ‘abcdefghijklmnopqrstuvwxyz‘;
$str = str_shuffle($str);
echo substr($str,0,4);//drifstrlen获得字符长度
$str1 = NULL;//0
$str2 = ‘AB‘;//2
$str3 = ‘中国‘;//6 一个中文3个字符
echo strlen($str1) , strlen($str2) , strlen($str3);stripos不区分大小写，字符串从0开始编号,如果没有出现，则返回FALSE
$str1 = ‘javascript‘;
$str2 = ‘A‘;
var_dump(stripos($str1, $str2)); //int(1)搜索$str2在字符串中的位置，并返回从该位置到字符串结尾的所有字符
$str1 = ‘abcdcef‘;
$str2 = ‘c‘;
echo strrchr($str1, $str2);//cef获取扩展名
$filename = ‘a.bc.cd.png‘;
echo substr(strrchr($filename, ‘.‘),1);//pngstrtoupper转大写
strtolower转小写
$str1 = ‘html‘;
$str2 = ‘PHP‘;
echo strtoupper($str1) , strtolower($str2);//HTMLphpucfirst句子首字母大写
ucwords单词首字母大写
$str3 = ‘this is a test‘;
echo ucfirst($str3) , ucwords($str3);substr截取字符串
负数=字符串长度+该负数
$str = ‘javascript‘;
echo strlen($str);//10
echo substr($str, 0,4) ;//java
echo substr($str, 4);//script
echo substr($str, -2);//pt -2=10-2=8
echo substr($str, -5,-2) , "\n";//cri -5,-2=5,8将字符串转为Zend_Controller_Front
$str = ‘ZenD_CONTRollER_FronT‘;
//1.转换小写
$str1 = strtolower($str);
//2.将下划线替换成空格
$str2 = str_replace(‘_‘, ‘ ‘, $str1);
//3.通过ucwords进行首字母大写操作
$str3 = ucwords($str2);
//4.将空格替换成下划线
$str4 = str_replace(‘ ‘, ‘_‘, $str3);
echo $str4;//Zend_Controller_Frontfloor() ceil()
$x = 2.7;
$y = 3.01;
echo floor($x) , ‘<br/><br/>‘;//2 向下取整
echo ceil($y) , ‘<br/><br/>‘;//4 向上取整假设记录数为X,每页显示Y条记录,求总页数z
z = ceil(X/Y);
fmod()对浮点数取模
echo fmod(7.8,3) , ‘<br/>‘;//1.8
对整数取模
echo 7.8 % 3 ; //整数余数的操作//1
格式化数字
$x = 7896.827;
echo number_format($x) , ‘<br/><br/>‘;//7,897
echo number_format($x,2) , ‘<br/><br/>‘;//7,896.83pow()幂操作 sqrt()平方根操作
echo pow(2,3);//8
echo sqrt(4) ;//2mt_rand()是更好的随机数生成器，因为它跟rand()相比播下了一个更好地随机数种子；而且性能上比rand()快4倍
echo rand(50,80);
echo mt_rand(10,99);生成四位数随机验证码
$chars = ‘abcdefghijlmnopqrstuvwxyz789654321‘;
$len = strlen($chars);
for($i=0;$i<4;$i++){
$char .= substr($chars,mt_rand(0,$len-1),1);
}
echo $char;round()四舍五入
$x = 7.238;
echo round($x);//7
echo round($x,2);//7.24strtotime字符串转时间
echo ‘当前日期:‘ , date(‘Y-m-d‘) , "\n";//2020-01-10
echo ‘下个月的日期：‘ , date(‘Y-m-d‘, strtotime(‘1 month‘)) , "\n";//2020-02-10
echo ‘上个月最后一天：‘ , date(‘Y-m-d H:i:s‘,strtotime(‘last day of -1 month‘)) , "\n";//2019-12-31 10:39:12
echo ‘上个月最后一天零点：‘ , date(‘Y-m-d H:i:s‘, strtotime("midnight last day of -1 month")) , "\n"; //2019-12-31 00:00:00
echo ‘昨天零点：‘ , date(‘Y-m-d H:i:s‘,strtotime(‘yesterday‘)) , "\n";//2020-01-09 00:00:00
echo ‘现在：‘ , date(‘Y-m-d H:i:s‘,strtotime(‘now‘)) , "\n";//2020-01-10 10:39:12
echo ‘三个星期之间的时间戳是:‘ , strtotime(‘-3 weeks‘);//三个星期之间的时间戳是:1576810790
echo (time() - strtotime(‘-3 weeks‘))/86400 ;//21 间隔时间
echo ‘上个月：‘.date(‘Y-m-d H:i:s‘,strtotime(‘-1 month‘)) ; //上个月：2019-12-10 10:59:50
echo ‘上个月的第一天：‘.date(‘Y-m-d H:i:s‘,strtotime(‘first day of -1 month‘));//上个月的第一天：2019-12-01 10:59:50返回当前本地的日期/时间的日期/时间信息
print_r(getdate());
//Array
//(
// [seconds] => 3
// [minutes] => 42
// [hours] => 10
// [mday] => 10
// [wday] => 5
// [mon] => 1
// [year] => 2020
// [yday] => 9
// [weekday] => Friday
//[month] => January
//[0] => 1578624123
//)microtime()返回当前 Unix 时间戳的微秒数
echo microtime();//0.41369400 1578624195
当设置为 TRUE 时，规定函数应该返回一个浮点数，否则返回一个字符串;默认为 FALSE
echo microtime(true);//1578624195.4137
计算程序运行时间
$start = microtime(true);
$sum = 0;
for ($i=0; $i <1000000 ; $i++) {
$sum += $i;
}
$end = microtime(true);
echo ‘共花费‘ , round($end - $start,3) , ‘秒‘;//共花费0.016秒time()
echo time() ;//1578625294
echo ‘当前的日期时间是:‘ , date(‘Y-m-d H:i:s‘) ;//当前的日期时间是:2020-01-10 11:01:34
echo ‘昨天的日期时间是:‘ , date(‘Y-m-d H:i:s‘,time()-86400) ; //24*60*60 //昨天的日期时间是:2020-01-09 11:01:34uniqid() 函数基于以微秒计的当前时间，生成一个唯一的 ID
echo uniqid();//5e17e94f8a19b
echo uniqid(‘abc‘);//abc5e17e96c1771e
echo uniqid(microtime());//0.09603300 15786253885e17e96c17727
echo uniqid(microtime() . mt_rand()); //mt_rand(100,999);//0.09604200 15786253884744704985e17e96c1772f
//uuid 8-4-4-4-12 = 32
echo md5(uniqid(microtime() . mt_rand()));//cf6333288fcb04f60fbbedafd127201esession
session_start();
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