<?php
//1.initiate an array
//1
$a = array(1, 2, 3);
//2
$b = [4, 5, 6];
//3
$numbers = range(1, 10); //1,2,3,4,5,6,7,8,9,10
$odds = range(1, 10, 2); //1,3,5,7,9
$odds = range(10, 1, -1); //9,7,5,3,1
$letters = range('a', 'z'); //a-z
echo '<pre>';
//var_dump($numbers);
//var_dump($odds);
//var_dump($letters);
$a[3] = 4; //automatically resize the array
//4
$student = ['amy', 'joseph', 'mike'];
//read array
for ($i = 0; $i < 3; $i++) {
// echo $student[$i];
}
foreach ($student as $name) {
//echo $name.'foreach';
}
//5
$grades = array('amy' => 89, 'joseph' => 99, 'mike' => 100);
//6
$grades = array('amy' => 89);
$grades['joseph'] = 99;
$grades['mike'] = 100;
//7
$grades['amy'] = 89;
$grades['joseph'] = 99;
$grades['mike'] = 100;
//2.using loops
foreach ($grades as $student => $grade) {
//echo $student.'='.$grade;
}
while ($element = each($grades)) {
//var_dump($element);
}
reset($grades); //because each() tracks every elements to next one,
// if you want to use the array again you need to reset it
while (list($stu, $grade) = each($grades)) {
//echo $stu.'='.$grade;
}
//3.sort
$student = ['zamy', 'joseph', 'mike'];
sort($student);//sort by ASCII
//print_r($student);
$file = array(file01, file06, file02);
sort($file, SORT_NATURAL);//sort by ASCII
//print_r($file);
$product = array('oil' => 100, 'tyre' => 58, 'plugs' => 45);
asort($product);//sort by value
//print_r($product);
ksort($product); //sort by key
//print_r($product);
//ascending above descending corespondingly are rsort(), arsort(), krsort();
$products = array(
array('eTLR', 'aTires', 100), //code, desc, price,x
array('gOIL', 'bOil', 10),
array('fSPK', 'cSpark Plugs', 4)
);
///for multi-mension array
array_multisort($products); //sort by the first element
//print_r($product);
//4.usort user-defined sort
function compare($x, $y)
{ // x is a kind of product
if ($x[0] == $y[0]) { //0 stands for eTLR,,,, 1 stands for aTires, 2 stands for 100
return 0;
} elseif ($x[0] > $y[0]) { //x > y return 1 then ascending, vice versas, if x<y, return 1, descending
return 1;
} else {
return -1;
}
}
usort($products, 'compare'); //compare is a "callable" ,also change the array, this function is from multi-mension arrays
//similarly there also other functions such as: uasort(), uksort(),
print_r($products);
shuffle($product);
$reversedArray = array_reverse($product); // there is no &, so this function does not change the product array, instead it returns a reverse array
$numbers = array();
for ($i = 10; $i > 0; $i--) {
array_push($numbers, $i); // add the end element of the nmubers
}
//print_r($numbers);
array_pop($numbers); //remove the end element from the numbers
//print_r($numbers);
$str = '123d3ll3';
echo intval($str); //123
//5.array pointer ： every array has a internal pointer that pointed the current element
$arr = array(1, 2, 3, 4, 5);
echo current($arr); //1
echo each($arr); //return array(1=>2) but pointer points to the next one 2
echo next($arr); // 3
echo end($arr); //5
echo prev($arr); //4
echo '<br/>';
//6. array_walk($arr,callable func[, mixed userData])
//applying any function to each element in a array. using array_walk($arr,callable func[, mixed userData])
// callable func is the name of a user-defined function that applies the same change to every element.
function myPrint($value)
{
echo "$value<br/>";
}
//this will not change the arr due to &,using for loop
array_walk($arr, "myPrint"); //myPrint is the name of the function,
print_r($arr);
echo "<hr>";
function myMultiply($v, $key, $factor){ //there is a sequence of $value and $key,
// the first one is the value and second is the key. $key is not used although declared here
$v *= $factor;
echo "$v<br/>";
}
//this will not change the arr due to & in the first parameter
function myMultiply(&$v, $k, $factor)
{ //&$v means that $v will be passed by reference
$v *= $factor;
echo "$v<br/>";
}
array_walk($arr, "myMultiply", 5); //
print_r($arr);
echo count($arr); //5
echo sizeof($arr); //5
//7.array_count_values();
//caculate the frequency of the element in a array
$arrF = array(1, 3, 4, 3, 3, 2, 4, 2, 1);
$ac = array_count_values($arrF);
print_r($ac); //k => v, 1 =>2 means 1 digit occurs 2 times in the arrF
echo "<hr>";
//8.extract();
$array = array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3');
extract($array);
echo $key1, $key2, $key3; //value1value2value3
//$key1,$key2,$key3 variables already exist
$arr2 = array('key1' => 'valueA', 'keyB' => 'valueB', 'keyC' => 'valueC');
extract($arr2);
//extract($arr2),EXTR_OVERWRITE); by default
echo $key1, $keyB, $keyC; //valueAvalueBvalueC
extract($array, EXTR_PREFIX_ALL, 'myPrefix'); //link variable with _
echo $myPrefix_key1, $myPrefix_key2, $myPrefix_key3; //value1value2value3
