Welcome! In this lesson, we'll delve into the basic string manipulation features of PHP, which include string tokenization, string concatenation, trimming whitespace from strings, and type conversion operations.

In PHP, we can use the explode function to tokenize a string, essentially splitting it into smaller parts or 'tokens'.

Using explode function:

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1<?php
2$sentence = "PHP is a versatile language!";
3$tokens = explode(" ", $sentence);
4
5foreach ($tokens as $token) {
6    echo $token . "\n";
7}
8?>

In the example above, we use a space as a delimiter to split the $sentence into words. This operation will print each word in the sentence on a new line.

In PHP, the . operator or implode function can be used to concatenate strings into a larger string:

Using the . Operator:

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1<?php
2$str1 = "Hello,";
3$str2 = " World!";
4$greeting = $str1 . $str2;
5echo $greeting;  // Output: "Hello, World!"
6?>

Using implode:

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1<?php
2$strings = array("Hello", " World!", " PHP", " functions!");
3$result = implode("", $strings);
4echo $result;  // Output: "Hello World! PHP functions!"
5?>

In the example above, implode is used to concatenate all the elements of an array into a single string.

In PHP, the trim function can remove both leading and trailing whitespaces from a string:

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1<?php
2$str = "    Hello, World!    "; // string with leading and trailing spaces
3$str = trim($str); // remove leading and trailing spaces
4echo $str; // Output: "Hello, World!"
5?>

In this example, trim is used to remove leading and trailing whitespaces from a string.

We can convert strings to numbers using functions like intval (string to integer) and floatval (string to float), and other data types to strings using simple concatenation or casting:

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1<?php
2$numStr = "123";
3$num = intval($numStr);
4echo $num . "\n";  // Output: 123
5
6$floatStr = "3.14";
7$pi = floatval($floatStr);
8echo $pi . "\n";  // Output: 3.14
9
10$age = 20;
11$ageStr = (string)$age;
12echo "I am " . $ageStr . " years old."; // Output: I am 20 years old.
13?>

In this code, we use intval, floatval, and simple casting for type conversions.

In some cases, we may need to combine all the methods discussed:

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1<?php
2$numbers = "1,2,3,4,6";
3$numArray = explode(",", $numbers);
4$sum = 0;
5
6foreach ($numArray as $numStr) {
7    $sum += intval($numStr);
8}
9
10$average = $sum / count($numArray);
11echo "The average is " . $average;  // Output: The average is 3.2
12?>

By integrating these methods, we can transform the string "1,2,3,4,6" into an array of integers, calculate their average, and display the result.

Great job! You've gained an overview of PHP's string manipulation features, including string concatenation, string tokenization, trimming whitespace from strings, and type conversions. Now, it's time to get hands-on with these concepts in the exercises that follow. Happy coding!