I am trying to learn PHP and stumbled across this problem of having bad keys in my array
i have this function
public function pdf_read_root()
{
$this->root = $this->pdf_resolve_object( $this->c, $this->pdf_find_root());
}
but $this->root is returning the wrong values, how do i get the individual contents, $this->c & $this->pdf_find_root to see what is being used in pdf_resolve_object
public function pdf_read_root()
{
$this->root = $this->pdf_resolve_object( $this->c, $this->pdf_find_root());
echo "<pre>";
echo "<br> Value of member variable c is: ". print_r($this->c, true);
echo "<br> Value of method pdf_find_root() is: ". print_r($this->pdf_find_root(),true);
echo "<br> Value of member variable root is: ". print_r($this->root, true);
echo "</pre>";
}
Related
I'm trying to cache an Object's method, so every time I call the Class and the method, it won't process again after first time.
Here is what I'm trying to achieve,
class App {
public $data = null;
public function print() {
if ( $this->data === null ) {
$this->data = "First time.";
}
else {
$this->data = "After first time.";
}
return $this->data;
}
}
$data = new App();
echo $data->print() . "<br>";
echo $data->print() . "<br>";
$data2 = new App();
echo $data2->print() . "<br>";
echo $data2->print() . "<br>";
Result
First time.
After first time.
First time.
After first time.
As you can see, it's processing the print() method again when I call it again in $data2.
Is it possible to cache so result will be
First time.
After first time.
After first time.
After first time.
For get your required constant output you need to
change the public variable inside the class to as static variable
Because public static variables share all the available instances of that class each time.
class App {
public static $data = null;
public function print() {
if ( self::$data === null ) {
self::$data = "First time.";
}
else {
self::$data = "After first time.";
}
return self::$data;
}
}
$data = new App();
echo $data->print() . "<br>";
echo $data->print() . "<br>";
$data2 = new App();
echo $data2->print() . "<br>";
echo $data2->print() . "<br>";
Result will be :
First time.
After first time.
After first time.
After first time.
I am learning php and created the below class, but I can't seem to figure out why it giving me the below errors which says:
144
Warning: Missing argument 1 for setters::set_a(), called in C:\xampp\htdocs\php\accessmod2.php on line 19 and defined in C:\xampp\htdocs\php\accessmod2.php on line 9
Notice: Undefined variable: value in C:\xampp\htdocs\php\accessmod2.php on line 11
<?php
class setters{
private $a = 144;
public function get_a(){
return $this->a;
}
public function set_a($value){
$this->a = $value;
}
}
$example = new setters();
echo $example->get_a()."<br />";
$example->set_a(15)."<br />";
echo $example->set_a()."<br />";
?>
You have to use a parameter for the set() function. But in your case, I think you just want to see if the set() function have work. So use the get() function.
So change to this :
echo $example->get_a()."<br />";
$example->set_a(15)."<br />";
echo $example->get_a()."<br />";
And the result is :
144
15
Check your last line:
echo $example->set_a()."<br />";
set_a() requires a parameter but it is empty. If you change it like this, it will work:
echo $example->set_a('someparameterhere')."<br />";
Your second call to ->set_a requires a parameter :
<?php
class setters{
private $a = 144;
public function get_a(){
return $this->a;
}
public function set_a($value){
$this->a = $value;
}
}
$example = new setters();
echo $example->get_a()."<br />";
$example->set_a(15)."<br />";
$example->set_a(23)."<br />"; // ◄■■■ PARAMETER FOR "SET_A".
?>
You can also use an "optional" parameter :
<?php
class setters{
private $a = 144;
public function get_a(){
return $this->a;
}
public function set_a( $value = -1 ){ // ◄■■■ OPTIONAL PARAMETER.
$this->a = $value;
}
}
$example = new setters();
echo $example->get_a()."<br />";
$example->set_a()."<br />"; // ◄■■■ OPTIONAL PARAMETER ($a = -1).
echo $example->get_a()."<br />"; // ◄■■■ NEW VALUE = -1.
?>
You are calling set_a twice.
After set, you need call get_a to show the value.
echo $example->get_a()."<br />";
$example->set_a(15)."<br />";
echo $example->get_a()."<br />";
I tried this code today! But it's not giving the output I expected.. this is my code..
<?php
namePrint('Rajitha');
function namePrint($name) {
echo $name;
}
wrap('tobaco');
function wrap($txt) {
global $name;
echo "Your username is ".$name." ".$txt."";
}
?>
This code will print on screen
RajithaYour username is tobaco
but I want to get
RajithaRajithaYour username is tobaco
My question is: why is the $name variable in the wrap function not working?
Thanks.
Never use echo inside function to output the result. And never use global for variables.
You used echo inside function and because of that you get unexpected output.
echo namePrint('Rajitha');
function namePrint($name){
return $name;
}
echo wrap('tobaco');
function wrap($txt){
//global $name;
return "Your username is ".namePrint('Rajitha')." ".$txt."";
}
Output using echo in function Codepad
RajithaRajithaYour username is tobaco
Output1 using return in function Codepad
RajithaYour username is Rajitha tobaco
If you want to wrap a function around another you could simply pass a closure as one of the arguments:
function wrap($fn, $txt)
{
echo "Your username is ";
$fn();
echo ' ' . $txt;
}
wrap(function() {
namePrint('Rajitha');
}, 'tobaco');
This construct is very delicate; using function return values is more reliable:
function getFormattedName($name) {
return $name;
}
echo getFormattedName('Jack');
Then, the wrap function:
function wrap($fn, $txt)
{
return sprintf("Your username is %s %s", $fn(), $txt);
}
echo wrap(function() {
return getFormattedName('Jack');
}, 'tobaco');
Another option would be to pass $name as a parameter to the wrap function.
<?php
$name = 'Rajitha';
function namePrint($name){
echo $name;
}
function wrap($txt, $name){
echo "Your username is " . $name . " ". $txt;
}
namePrint($name);
wrap('tobaco', $name);
?>
$name should be declared and initialized as global variable.then you can the output you need.
The code should look like this.
<?php
$name = 'Rajitha';
namePrint($name);
function namePrint($name){
echo $name;
}
wrap('tobaco');
function wrap($txt){
global $name;
echo "Your username is ".$name." ".$txt."";
}
?>
I am new to PHP and need your help here. I know the basic functionality of this in PHP.
class SwapClass
{
public $num1 = 0;
public $num2 = 0;
function __construct($val1,$val2)
{
echo "In constructor!!" . "<br />";
$num1 = $val1;
$num2 = $val2;
}
public function display()
{
echo "1st value : " . $num1 . "<br />2nd value : " . $num2;
}
}
This is my class. I called it as:
$obj = new SwapClass(2,3);
$obj->display();
The values never come to the display() method. I tried echoing it in the constructor. It's confirmed that values are coming. I then modified the code to:
class SwapClass
{
public $num1 = 0;
public $num2 = 0;
function __construct($val1,$val2)
{
echo "In constructor!!" . "<br />";
$this->num1 = $val1;
$this->num2 = $val2;
}
public function display()
{
echo "1st value : " . $this->num1 . "<br />2nd value : " . $this->num2;
}
}
It works fine now. Why does can't the variables be accessed without this?
Is this used for disambiguation? In my example I have just one object. So what is the problem?
Any member of class is recognized buy using $this in class.
Otherwise it will be treated as local variable where it is being used.
It does not depend on number of object of class, You need to use it for one object as well as for hundreds and more.
http://tournasdimitrios1.wordpress.com/2010/10/11/using-the-keyword-this-in-php/
function func() {
// ...
}
I have the function name "func", but not its definition.
In JavaScript, I'd just use alert() to see the definition.
Is there a similar function in PHP?
You can use the methods getFileName(), getStartLine(), getEndLine() defined in ReflectionFunctionAbstract to read the source code of functions/methods from their source file (if there is any).
e.g. (without error handling)
<?php
printFunction(array('Foo','bar'));
printFunction('bar');
class Foo {
public function bar() {
echo '...';
}
}
function bar($x, $y, $z) {
//
//
//
echo 'hallo';
//
//
//
}
//
function printFunction($func) {
if ( is_array($func) ) {
$rf = is_object($func[0]) ? new ReflectionObject($func[0]) : new ReflectionClass($func[0]);
$rf = $rf->getMethod($func[1]);
}
else {
$rf = new ReflectionFunction($func);
}
printf("%s %d-%d\n", $rf->getFileName(), $rf->getStartLine(), $rf->getEndLine());
$c = file($rf->getFileName());
for ($i=$rf->getStartLine(); $i<=$rf->getEndLine(); $i++) {
printf('%04d %s', $i, $c[$i-1]);
}
}
I don't know of one.See code at bottom. There is a function to list all the defined functions. There's another to get the values of all the arguments to the current function, and the number of arguments. And there's one to see if a function exists. But there doesn't seem to be one to name the current function, nor any means of listing formal parameters.
Even when a runtime error occurs, it doesn't list a call stack, nor state the function that's active:
PHP Warning: Division by zero in t.php on line 6
Edit: For the code to identify where it is, add this:
echo "At line " .__LINE__ ." of file " . __FILE__ ."\n";
It gives the output
At line 7 of file /home/wally/t.php
Edit 2: I found this function in my code which looks to be what you want:
function traceback ($showvars)
{
$s = "";
foreach (debug_backtrace($showvars) as $row)
{
$s .= "$row[file]#$row[line]: ";
if(isset($row['class']))
$s .= "$row[class]$row[type]$row[function]";
else $s .= "$row[function]";
if (isset($row['args']))
$s .= "('" . join("', '",$row['args']) . "')";
$s .= "<br>\n";
}
return $s;
}
For example, it produces:
[wally#zf ~]$ php -f t.php
/home/wally/t.php#24: traceback('1')<br>
/home/wally/t.php#29: t('1', '2', '3')<br>
/home/wally/t.php#30: x('2', '1')<br>
/home/wally/t.php#31: y('2', '1')<br>
/home/wally/t.php#33: z('1', '2')<br>