Data Formats

📂 PHP Data Formats: Your Universal Translator

Imagine you’re a translator who can speak every language in the world. Data formats in PHP are exactly like that—they help your programs talk to files, databases, and other applications in languages they understand!

🎯 What You’ll Master

Think of data like LEGO blocks. Different systems use different shapes of blocks:

• CSV = Simple rows of blocks, like a shopping list
• JSON = Nested blocks that fit inside each other, like a toy box
• XML = Labeled blocks with tags, like organized drawers

PHP is your master builder that can read and create all these block types!

📋 CSV Reading: Opening Your Treasure List

What is CSV?

CSV stands for Comma-Separated Values. It’s like a simple list where each item is separated by a comma.

Real Life Example:

• Your mom’s grocery list: milk, eggs, bread, butter
• That’s CSV! Each word is separated by a comma.

How to Read CSV in PHP

$file = fopen("fruits.csv", "r");

while (($row = fgetcsv($file)) !== false) {
    echo $row[0] . " costs " . $row[1];
}

fclose($file);

What’s happening here?

1. fopen() = Open the treasure chest (file)
2. fgetcsv() = Read one line and split by commas
3. $row[0] = First item, $row[1] = Second item
4. fclose() = Close the chest when done

💡 Simple Analogy

Reading CSV is like reading a list where a friend put commas between items. You just split by commas and you have an array!

graph TD
    A["CSV File"] --> B["fopen - Open File"]
    B --> C["fgetcsv - Read Row"]
    C --> D{More Rows?}
    D -->|Yes| C
    D -->|No| E["fclose - Close File"]

✏️ CSV Writing: Creating Your Own Lists

Making a CSV File

Just like you can read a list, you can write one too!

$file = fopen("scores.csv", "w");

$students = [
    ["Alice", 95],
    ["Bob", 87],
    ["Carol", 92]
];

foreach ($students as $student) {
    fputcsv($file, $student);
}

fclose($file);

The result in scores.csv:

Alice,95
Bob,87
Carol,92

🔑 Key Function: fputcsv()

Pro tip: PHP automatically adds commas between array items and puts each row on a new line!

🔐 JSON Encoding: Packing Your Toy Box

What is JSON?

JSON stands for JavaScript Object Notation. Think of it as a labeled toy box where everything has a name.

{
    "name": "Teddy",
    "color": "brown",
    "size": "medium"
}

Converting PHP to JSON

$pet = [
    "name" => "Fluffy",
    "type" => "cat",
    "age" => 3
];

$json = json_encode($pet);
echo $json;

Output:

{"name":"Fluffy","type":"cat","age":3}

Making JSON Pretty

$json = json_encode($pet, JSON_PRETTY_PRINT);

Now it looks like:

{
    "name": "Fluffy",
    "type": "cat",
    "age": 3
}

graph TD
    A["PHP Array"] --> B["json_encode"]
    B --> C["JSON String"]
    C --> D["Send to API"]
    C --> E["Save to File"]
    C --> F["Send to Browser"]

🔓 JSON Decoding: Unpacking the Toy Box

Reading JSON Back to PHP

$json = '{"name":"Max","age":5}';

$data = json_decode($json, true);

echo $data["name"]; // Max
echo $data["age"];  // 5

The Magic Second Parameter

💡 Real World Example

When you get weather data from an app:

$weather = '{"city":"Tokyo","temp":22}';
$info = json_decode($weather, true);

echo "It's " . $info["temp"] . "° in " . $info["city"];
// Output: It's 22° in Tokyo

⚠️ JSON Error Handling: Catching Mistakes

Why Errors Happen

Sometimes JSON is broken—like a puzzle with missing pieces!

$badJson = '{"name": "Sam",}'; // Extra comma!

$data = json_decode($badJson);

if (json_last_error() !== JSON_ERROR_NONE) {
    echo "Oops! " . json_last_error_msg();
}

Common JSON Errors

The Safe Way to Handle JSON

$json = '{"valid": "data"}';
$result = json_decode($json, true);

if ($result === null && json_last_error()) {
    echo "Error: " . json_last_error_msg();
} else {
    echo "Success! Name: " . $result["valid"];
}

graph TD
    A["JSON String"] --> B["json_decode"]
    B --> C{Check Error}
    C -->|No Error| D["Use Data ✅"]
    C -->|Has Error| E["json_last_error_msg"]
    E --> F["Handle Error ⚠️"]

📦 XML Parsing with SimpleXML: Reading Labeled Boxes

What is XML?

XML uses tags like labels on boxes. Everything has an opening and closing tag.

<book>
    <title>PHP for Kids</title>
    <author>Jane Doe</author>
    <pages>150</pages>
</book>

Loading XML in PHP

$xml = simplexml_load_string('
<pet>
    <name>Buddy</name>
    <type>dog</type>
</pet>
');

echo $xml->name; // Buddy
echo $xml->type; // dog

Loading from a File

$books = simplexml_load_file("library.xml");

foreach ($books->book as $book) {
    echo $book->title . " by " . $book->author;
}

Working with Attributes

XML can have attributes like sticky notes on boxes:

<product id="123" stock="50">
    <name>Toy Car</name>
</product>

$product = simplexml_load_string($xmlString);

echo $product["id"];     // 123 (attribute)
echo $product->name;     // Toy Car (element)

🗺️ XML Navigation Map

graph TD
    A["XML String/File"] --> B{Load Method}
    B -->|String| C["simplexml_load_string"]
    B -->|File| D["simplexml_load_file"]
    C --> E["SimpleXML Object"]
    D --> E
    E --> F["Access Elements: $xml->element"]
    E --> G["Access Attributes: $xml['attr']"]
    E --> H["Loop: foreach $xml->item"]

🎯 Quick Comparison: Which Format to Use?

🚀 Your Data Format Superpowers

You now have three superpowers:

1. CSV Power 📋

   • Read lists with fgetcsv()
   • Write lists with fputcsv()

2. JSON Power 🔐

   • Pack data with json_encode()
   • Unpack with json_decode()
   • Check errors with json_last_error()

3. XML Power 📦

   • Load with simplexml_load_string() or simplexml_load_file()
   • Access elements with -> and attributes with []

💡 Remember This!

CSV is like a simple grocery list JSON is like a labeled toy box XML is like organized drawers with name tags

Each format is a different language. PHP helps you speak them all!

Now you’re ready to make your programs talk to the whole world! 🌍