PHP language basic study notes_PHP tutorial

I spent an hour reviewing PHP, which I haven’t touched in many years, and marked it. I learned it in my sophomore year of high school.

1. The code is embedded in

2. Output function echo, equivalent to document.write in js

3. You can use single quotes when printing double quotes or use single quotes when printing double quotes.

echo 'She said,"how you are?"';

echo "she said,'how you are?'";

4. You can use the same quotation marks or print symbols that need to be escaped, echo 'I 'm just ducky.'; echo "she said, "How are you?"";

5. It is recommended to use shell style for comments, #this is a comment

6. The variable is the same as c, preceded by $.

echo $money;

echo "hello,$money";

7. Connection string $aa = "sdfs";$bb = "fsdfs"; $cc = $aa.$bb;

$cc = $cc."fsdfs";

8. About numbers

$n = 2.13;

$n = round($n); //3 Rounded

$n = 3.13141;

$n = round($n,3); //3.131 rounding of reserved digits

$n = number_format($n); //Add separator

$n = number_format($n,4);//Set the separator for the number of digits

9.Constant

define('NAME','VALUE');

echo NAME;

10.get is used to initiate data requests, and post users send data in one direction

11.$_REQUEST is a super global variable, which is a collection of $_POST and $_GET

12.isset() function is used to determine whether a variable has a value

13.empty() function is used to determine whether a variable is empty

14. Check whether it is a number using the is_numeric function

15. Array

$band[] = "sdfs";

$band[] = "sdfs";

$ band[] = "huhu";

$state = array(key1 => value1,key2 => value2....);

Key-value correspondence echo $state[key1];

foreach($array as $key =>$value){

}

Two-dimensional array

$array2 = (key1=>array1,.....);

16. Sorting

sort by value, reset the key value relationship

asort sorts by value and maintains key-value relationships

ksort sort by key

rsort,arsort,krsort reverse sorting

17. Loop judgment briefly

18.Included files

include(url);

require(url); //can be included multiple times

include_once(url);

require(url); //can only be included once

19. Processing html forms

if($isset($_POST['submitted'])){

}

else{

}

20.$page_title sets the title

21. Set up sticky form

22. Function reference js function

Note that an array can be returned

For example return array($avariable1,$avariable2);

You can set default parameters

function greet($name,$msg = "hello"){

}

23. If you want the variables within the function to be used externally, you can use global

function xxx(){

global $fsdf;

}

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