Day 38 (PHP)

1.除错查看var_dump、echo gettype，看变数有没有错

    echo gettype($var2) . '<hr />';  //array
    var_dump($var2); //array(1) { [7]=> int(123) }

<?php

    $ary1 = array(1, 2.3, false, 'Brad',5);

    echo gettype($ary1); 
    //array

    var_dump($ary1);
    //arrayarray(5) 
    //{ [0]=> int(1) [1]=> float(2.3) [2]=> bool(false) [3]=> string(4)"Brad" 
    //  [4]=> int(5) }
    
?>

2.若错误显示offset，指阵列

    $ary1 = array(1, 2, 3, 4);
    echo $ary1[4] . '<hr />';  //错误

3.几个元素count

    $ary1 = array(1, 2, 3, 4);
    echo count($ary1) . '<hr />';

4.查看阵列内每个值foreach，看key =>(的) vaule

               //key:vaule
    $person['name'] = 'Brad';
    $person['age'] = 18;
    $person['gender'] = true;
    $person[1] = 123;

    foreach ($person as $key => $value) {
        echo "{$key} : {$value}<br />";
    }

5.阵列

JS阵列是物件的一种(阵列表现出Array)
PHP阵列，是资料结构，比较像python的dictionary

6.阵列中指定key,会接续下去 =>

    $p = array(7 => 0, 0, 0, 77 => 0, 0, 0);
    var_dump($p);
    //array(6) { [7]=> int(0) [8]=> int(0) 
    //[9]=> int(0) [77]=> int(0) [78]=> int(0) [79]=> int(0) }

7. $p[$point]++

    $p = array(1 => 0, 0, 0, 0, 0, 0);
    //阵列从1开始
    for ($i = 0; $i < 1000000; $i++) {

    $point = rand(1, 6); //乱数1~6
    $p[$point]++;  //p内[阵列] 乱数如果1，开[1]里面+1(++)