PHP study notes 2

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1 , IF...ELSE statement

is the same as C language.

<?php
$t=date("H");
if ($t<"10")
{
    echo "Have a good morning!";
}
elseif ($t<"20")
{
    echo "Have a good day!";
}
else
{
    echo "Have a good night!";
}
?>

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2. SWITCH statement

is the same as C language. <br/>

<?php
$favcolor="red";
switch ($favcolor)
{
case "red":
    echo "你喜欢的颜色是红色!";
    break;
case "blue":
    echo "你喜欢的颜色是蓝色!";
    break;
case "green":
    echo "你喜欢的颜色是绿色!";
    break;
default:
    echo "你喜欢的颜色不是 红, 蓝, 或绿色!";
}
?>

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3. While loop

(1)while

(2)do...while will at least execute Code once and then check the condition

<br/>

# same as C language.

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4. For loop - know in advance the number of times the script needs to be run

(1) for

(2) foreach is used Traverse array

<?php
$x=array("one","two","three");
foreach ($x as $value){
    echo $value . "<br>";
}
?>

<br/>

<br/>

<br/>

5, array

<br/>

In PHP, array () function is used to create arrays. <br/>

<?php
$cars=array("Volvo","BMW","Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>

<br/>

(1) Array type

The first type: numerical array, automatic allocation of ID values ​​and manual allocation of ID values<br/>

<br/>

<br/>

Get the length of the array - count() function, for example: count($cars);

Traverse the values Array - for loop

<?php
$cars=array("Volvo","BMW","Toyota");
$arrlength=count($cars);
 
for($x=0;$x<$arrlength;$x++){
    echo $cars[$x];
    echo "<br>";
}
?>

<br/>

Second type: Associative array, without ID, using the specified key assigned to the array<br/>

<?php
$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");
echo "Peter is " . $age[&#39;Peter&#39;] . " years old.";
?>

<br/>

Traverse associative array - foreach loop<br/>

<?php
$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");
 
foreach($age as $x=>$x_value){
    echo "Key=" . $x . ", Value=" . $x_value;
    echo "<br>";
}
?>

<br/>

##(2) Array sorting (function)

First Type: sort(), ascending sort

<br/>

<pre class="brush:php;toolbar:false"> 
<?php 
$cars=array("Volvo","BMW","Toyota");  
sort($cars);  
print_r($cars); 
?> 

<br/>

Result:

Second type: rsort( ), sort in descending order

<br/>

<br/>

<br/>

The third type: asort(), sorts the array in ascending order according to the value of the array ( For associative arrays)

The fourth method: ksort(), sorts the array in ascending order according to the keys of the array

<br/>

<br/>

The fifth type: arsort(), sort in descending order according to the value of the array

The sixth type: krsort(), sort in descending order according to the key of the array

<br/>

<br/>

6. Super global variables

are available in the entire scope of a script.

<br/>

<br/>

(1) $GLOBALS

$GLOBALS is a global combination array containing all variables. The name is the key of the array.

<?php 
$x = 75; 
$y = 25;
 
function addition() { 
    $GLOBALS[&#39;z&#39;] = $GLOBALS[&#39;x&#39;] + $GLOBALS[&#39;y&#39;]; 
}
 
addition(); 
echo $z; //z是一个$GLOBALS数组中的超级全局变量，同样可以在函数外部访问
?>

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(2)$_SERVER

$_SERVER is a server that contains information such as header, path, and script locations. ) and other information. The items in this array were created by the web server. There is no guarantee that all items will be available on every server.

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<br/>

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(3) $_REQUEST

$_REQUEST is used to collect data submitted by HTML forms.

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<br/>##(4)$_POST

$_POST is used to collect form data

<br/>

<br/>(5)$_GET

$_GET should be used to collect form data

<br/>

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<br/>7. Function

<br/>

<br/> (1) PHP built-in Function

(2) Function

<br/>

##Format: function functionName(...){..... .}<br/>

Guidelines: functionName starts with a letter or underscore

Note that the return value type does not need to be specified

<?php
function add($x,$y)
{
    $total=$x+$y;
    return $total;
}
 
echo "1 + 16 = " . add(1,16);
?>

Related recommendations:

PHP learning Note 1

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