PHP JSON file: Read and convert to an associative array

PHP File Handling: Exercise-17 with Solution

Write a PHP function that reads a JSON file and returns the decoded data as an associative array.

Sample json file (people.json)

  "people" : [
       "firstName": "Joe",
       "lastName": "Jackson",
       "gender": "male",
       "age": 28,
       "number": "7349282382"
       "firstName": "James",
       "lastName": "Smith",
       "gender": "male",
       "age": 32,
       "number": "5678568567"
       "firstName": "Emily",
       "lastName": "Jones",
       "gender": "female",
       "age": 24,
       "number": "456754675"

Sample Solution:

PHP Code :

function readJSONFile($filename) {
    try {
        $jsonContents = file_get_contents($filename);

        if ($jsonContents === false) {
            throw new Exception("Error reading the JSON file.");

        $decodedData = json_decode($jsonContents, true);

        if ($decodedData === null) {
            throw new Exception("Error decoding the JSON data.");

        return $decodedData;
    } catch (Exception $e) {
        echo "An error occurred: " . $e->getMessage();

// Usage:
$filename = "i:/people.json";
$data = readJSONFile($filename);

// Example usage of the returned associative array:
foreach ($data["people"] as $person) {
    echo "Name: " . $person["firstName"] . " " . $person["lastName"] . "</br>";
    echo "Age: " . $person["age"] . "</br>";
    echo "Gender: " . $person["gender"] . "</br>";
    echo "Number: " . $person["number"] . "</br>";
    echo "------------------------</br>";

Sample Output:

Name: Joe Jackson
Age: 28
Gender: male
Number: 7349282382
Name: James Smith
Age: 32
Gender: male
Number: 5678568567
Name: Emily Jones
Age: 24
Gender: female
Number: 456754675


In the above exercise -

  • First, we use file_get_contents() to read the JSON file contents into a string variable named $jsonContents. If there is an error reading the file (e.g., the file doesn't exist or is not readable), we throw an exception with the message "Error reading the JSON file."
  • We then use json_decode($jsonContents, true) to decode the JSON string into a PHP associative array. The second argument true specifies that we want an associative array rather than an object. If there is an error decoding the JSON data (e.g., the JSON format is invalid), we throw an exception with the message "Error decoding the JSON data."
  • If the file is successfully read and the JSON data is decoded, we return the resulting associative array from the function.
  • After the function definition, we have an example usage section where we call the readJSONFile($filename) function. In this example, we pass the filename "i:/people.json" to the function and store the returned associative array in a variable named $data.
  • We then iterate over the "people" array within the $data associative array using a foreach loop. For each person, we access their properties (firstName, lastName, age, gender, and number) and display them using echo. We add HTML line breaks (</br>) to format the output.


Flowchart: Read and convert to an associative array

PHP Code Editor:

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