Learn PHP record "three"

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1, string

string concatenation, string is no + this operator, so is:

$a = ' Hello '; $a . = ' World '; Echo $a ; # back to Hello world

$a = ' Hello '; $b $a . ' World '; Echo $b ; # result "HelloWorld

To manipulate a string, it is operated by subscript.

1<?PHP2 //gets the first character of a string3 $str= ' This is a test. ';4 $first=$str[0];5 6 //gets the third character of a string7 $third=$str[2];8 9 //gets the last character of the stringTen $str= ' This is still a test. '; One $last=$str[strlen($str)-1];  A  - //Modify the last character of a string - $str= ' Look at the sea '; the $str[strlen($str)-1] = ' E '; -  -?>

2. Array

Now you can define it directly through [] and it feels good.

$a = [

' Foot ': ' H ',

]

Delete a data

unset ($a [' foot ']);

However, the index of key is not re-established after deletion, and the code is attached:

<? PHP $a Array (1 = ' one ', 2 = ' one ', 3 = ' three '); unset ($a[2]); /* Would produce an array that would has been defined   as $a = array (1 = ' one ', 3 = ' three ');   And not   $a = array (1 = ' one ', 2 = ' three '); */

Delete all data:

foreach ($aas$i$value):    unset($a [$i]);

Print an array

Print_r ($a);

To calculate the size of an array:

$count Count ($array);

If you want to reassign value, you can do so by referencing it in the loop:

But this kind of no-brain change should seldom be used;

$arr = [' a ' = = ' B ']; foreach ($arr as$key=>&$value) {    $value= ' Test ';}

Add an official example:

<? PHP foreach (array as &$value) {    $value$value * 2 ;}? >

Learn PHP record "three"