Display String

$technology = "PHP";
echo $technology;

$technology = "PHP";
print $technology;

$technology = "PHP";
<?= $technology ?>

---

Concatenation

$action = "Learn";
$technology = "PHP";
echo $action . $technology;

$action = "Learn";
$technology = "PHP";
echo "$action $technology";

$technology =  "PHP";
$version = 7.3;
$web_based = true;
echo "Technology: " . $technology . ", Version: " , $version . ", Web: " . $web_based;

---

heredoc (for documentation)

$dev = "Web Development";
$amount = 10;

// just prints whatever is written inside the block, no operation is performs except variable substitution.
echo <<< DOC_DEV
"PHP" seems very simple language. Very cool language for $dev. ($amount * 10)
DOC_DEV 

---

nowdoc (for documentation - write the label in single quotes)

$dev = "Web Development";
$amount = 10;

// just prints whatever is written inside the block, no variable substitution.
echo <<< 'DOC_DEV'
"PHP" seems very simple language. Very cool language for $dev. ($amount * 10)
DOC_DEV 

---

String Length

$language = "PHP";
$subject = "  ";
$teacher = "";
echo strlen($language);
echo strlen($subject);
echo strlen($teacher);
echo strlen($class); // variable is not defined, the strlen will return 0

if (strlen($fullName) > 0) {
      echo $fullName;
}
else {
      echo "not defined, empty or null";
}

---

String Position

// strpos() search is case sensitive
$subject = "Welcome to the Learning PHP Website";

$stringToFind = "W";
$stringPosition = strpos($subject, $stringToFind);
echo $stringPosition;

$stringToFind = "P";
$stringPosition = strpos($subject, $stringToFind);
echo $stringPosition;

$stringToFind = "website";
$stringPosition = strpos($subject, $stringToFind);
echo $stringPosition; // this will not output anything due to case sensitivity. The letter W is in lower case. It is false.

// stripos() search is case insensative
$subject = "Welcome to the Learning PHP Website";
$stringToFind = "LEARNING";
$stringPosition = stripos($subject, $stringToFind);
echo $stringPosition;

---

Word Count

$suject = "Welcome to the Learning PHP Website";
echo "Total words: " . str_word_count($subject);

---

Replace String

$suject = "Welcome to the Learning PHP Website";
echo str_replace("Welcome", "Hello and welcome", $subject);

---

Reverse String

$suject = "Mars";
echo strrev($subject);

---

Shuffle String

$suject = "Welcome to the Learning PHP Website";
echo str_shuffle($subject);

---

Uppercase & Lowercase

$suject = "Welcome to the Learning PHP Website";
echo strtoupper($subject);
echo strtolower($subject);

---

Wordwrap

$suject = "Welcome to the Learning PHP Website";
echo wordwrap($subject, 5, "<br />", true); // true menas, break the word if the length reaches to 5

$suject = "Welcome to the Learning PHP Website";
echo wordwrap($subject, 20, "<br />", false); // false menas, do not break the word if the length reaches to 20

---

String Trim

$suject = " Welcome to the Learning PHP Website  ";
echo strlen($subject);
echo strlen(ltrim($subject));
echo strlen(rtrim($subject));
echo strlen(trim($subject));