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)));//jpeg

trim移除字符串两侧的字符

$str = "\n\n\t\tABC\t\t";
    echo trim($str);//ABC

md5()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:123

htmlspecialchars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&gt;B,B&lt;C,Tom&amp;John,He said:&quot;I&#039;m OK&quot;

通过str_replace进行转换

$str1 = str_replace(‘&‘, ‘&amp;‘, $str); //必须是第一阶梯
    $str2 = str_replace(‘>‘, ‘&gt;‘, $str1);
    $str2 = str_replace(‘<‘, ‘&lt;‘, $str2);
    $str2 = str_replace(‘"‘, ‘&quot;‘, $str2);
    $str2 = str_replace(‘\‘‘, ‘&#39;‘, $str2);
    echo $str2;//A&gt;B,B&lt;C,Tom&amp;John,He said:&quot;I&#039;m OK&quot;

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);//drif

strlen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);//png

strtoupper转大写
strtolower转小写

$str1 = ‘html‘;
    $str2 = ‘PHP‘;
    echo strtoupper($str1) , strtolower($str2);//HTMLphp

ucfirst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_Front

floor() 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/>‘;//7,896.83

pow()幂操作 sqrt()平方根操作

echo pow(2,3);//8
    echo sqrt(4) ;//2

mt_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);//7.24

strtotime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 11:01:34

uniqid() 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()));//cf6333288fcb04f60fbbedafd127201e

session

session_start();
    echo session_id();//bp99jhu204h6vi214ttgcjce80

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