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PHP find output programs (JSON) | set 1

Find the output of PHP programs | JSON | Set 1: Enhance the knowledge of PHP JSON by solving and finding the output of some PHP programs.
Submitted by Nidhi, on January 27, 2021

Question 1:

<?php
    $student = array(
        "Rahul" => 101,
        "Rohit" => 102,
        "Virat" => 103
    );
    $JSON_STR = encode_json($student);
    
    echo $JSON_STR;
?>

Output:

PHP Fatal error:  Uncaught Error: Call to undefined function encode_json() 
in /home/main.php:7
Stack trace:
#0 {main}
  thrown in /home/main.php on line 7

Explanation:

The above program will generate compilation error, because encode_json() is not a built function in PHP. The json_encode() function is used to encode an array into JSON format.

Question 2:

<?php
    $student = array(
        "Rahul" => 101,
        "Rohit" => 102,
        "Virat" => 103
    );
    
    $JSON_STR = json_encode($student);
    $STR = json_decode($JSON_STR);
    
    var_dump($STR);
?>

Output:

object(stdClass)#1 (3) {
  ["Rahul"]=>
  int(101)
  ["Rohit"]=>
  int(102)
  ["Virat"]=>
  int(103)
}

Explanation:

In the above program, we created an array $student that contain student information. Then we encode array into JSON format and assigned to $JSON_STR and then we decode $JSON_STR using json_decode() function and assigned to $STR. Then we call var_dump() function and pass $STR to it then the above output will print on the webpage.

Question 3:

<?php
    $student = array(
        "Rahul" => "ABC",
        "Rohit" => "PQR",
        "Virat" => "XYZ"
    );
    
    $JSON_STR = json_encode($student);
    $STR = json_decode($JSON_STR);
    
    echo $STR->ABC . '<br>';
    echo $STR->PQR . '<br>';
    echo $STR->XYZ . '<br>';
?>

Output:

PHP Notice:  Undefined property: stdClass::$ABC in /home/main.php on line 11
PHP Notice:  Undefined property: stdClass::$PQR in /home/main.php on line 12
PHP Notice:  Undefined property: stdClass::$XYZ in /home/main.php on line 13  

Explanation:

In the above program, we created an associative array that contains keys ("Rahul", "Rohit", "Virat") and values ("ABC","PQR","XYZ"). Then we encode string $student and then we decode json_decode() into $STR.

Here, we access values directly using operator '->', we can access array values using specified keys.

echo $STR->Rahul.'<br>';
echo $STR->Rohit.'<br>';
echo $STR->Virat.'<br>';

In the above, echo statements we accessed values of associative array.

Question 4:

<?php
    $student = array(
        "Rahul" => "ABC",
        "Rohit" => "PQR",
        "Virat" => "XYZ"
    );
    
    $JSON_STR = json_encode($student);
    $STR = json_decode($JSON_STR);
    
    echo $STR['Rahul'] . '<br>';
    echo $STR['Rohit'] . '<br>';
    echo $STR['Virat'] . '<br>';
?>

Output:

PHP Fatal error:  Uncaught Error: Cannot use object of type stdClass as array 
in /home/main.php:11
Stack trace:
#0 {main}
  thrown in /home/main.php on line 11

Explanation:

In the above program, we created an associative array that contains keys ("Rahul", "Rohit", "Virat") and values ("ABC","PQR","XYZ"). Then we encode string $student and then we decode json_decode() into $STR.

The above program will generate syntax error, because $STR is not an array. it is an object returned by json_decode() function.

The correct way is given below,

echo $STR->Rahul.'<br>';
echo $STR->Rohit.'<br>';
echo $STR->Virat.'<br>';

Question 5:

<?php
    $student = array(
        "Rahul" => "ABC",
        "Rohit" => "PQR",
        "Virat" => "XYZ"
    );
    
    $JSON_STR = json_encode($student);
    $STR = json_decode($JSON_STR);
    
    foreach ($STR as $key => $value) 
        echo $key . " => " . $value . "<br>";
?>

Output:

Rahul => ABC
Rohit => PQR
Virat => XYZ

Explanation:

In the above program, we created an associative array that contains keys ("Rahul", "Rohit", "Virat") and values ("ABC","PQR","XYZ"). Then we encode string $student and then we decode json_decode() into $STR.

Then we accessed keys and values using foreach loop and print them on the webpage.

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