Strings and Arrays

Strings and Arrays

String Is a sequence of characters. Example: “hello” , “how are you?” , “123”,and “!@#$%” are all valid string values.

Creating and Accessing a String $myString = ‘hello‘; $myString = “hello”; <?php $myString='hello there!'; echo "Hello $myString"; echo 'Hello $myString'; ?>

{ } use the curly brackets to distinguish the variable name from the rest of the string $myFavorite=”cat”; echo “My favorite animals are {$myFavorite}s”;

Accessing Characters within a String $myString=”hello world”; echo $myString[0]; // displays h

String Functions • strlen() - Calculating length of array <?php $name = “Simon Stobart”; $stringlength = strlen($name); echo $stringlength; ?>

String Functions str_word_count() - returns the number of words in a string echo str_word_count(“Hello There”); // returns 2

String Functions Substr() - extract sequence of characters in a string The string to extract the characters from The position to start extracting the characters. If you use a negative number, substr() counts backward from the end of the string The number of characters to extract. If you use a negative number, substr() misses that many characters from the end of the string instead. This parameter is optional; if left out, substr()extracts from the start position tothe end of the string

$myString = “Hello, world!”; echo substr( $myString, 0, 5 ) . “ ”; // Displays ‘Hello’ echo substr( $myString, 7 ) . “ ”; // Displays ‘world!’ echo substr( $myString, -1 ) . “ ”; // Displays ‘!’ echo substr( $myString, -5, -1 ) . “ ”; // Displays ‘orld’

String Functions strpos() - find out exactly where a string of text occurs within another string $myString = “Hello, world!”; echo strpos( $myString, “wor” ); // Displays ‘7’ echo strpos( $myString, “xyz” ); // Displays ‘’ (false)

strrpos() - finds the last match in the string, rather than the first $myString = “Hello, world!”; echo strpos( $myString, “o” ) . “ ”; // Displays ‘4’ echo strrpos( $myString, “o” ) . “ ”; // Displays ‘8’

String Functions substr_count() - returns the number of times the text was found in the string $myString = “I say, nay, nay, and thrice nay!”; echo substr_count( $myString, “nay” ); // Displays ‘3’

String Functions strpbrk() - returns the portion of the string from the first matched character to the end of the string. If none of the characters in the set are found in the string, strpbrk() returns false .

$myString = “Hello, world!”; echo strpbrk( $myString, “abcdef” ); // Displays ‘ello, world!’ echo strpbrk( $myString, “xyz” ); // Displays ‘’ (false) $username = “matt@example.com”; if ( strpbrk( $username, “@!” ) ) echo “@ and ! are not allowed in usernames”;

String Functions • strstr(searchstring, lookingstring) • find a specific part of a string inside another string, returns the remainder of the input string <?php $name = “Simon Stowart”; $strOutput =strstr($name,”St”); echo “The result is”.$strOutput; ?>

String Functions • str_replace(lookingforstring,replatestring,searchstring) • Replace parts of the string with another string

<?php $strSentence="The use of italics can be useful to highlight certain words. "; $strOutput = str_replace("italics","italics",$strSentence); echo $strSentence ." "; echo "The output now looks like: ".$strOutput;?> ?>

String Functions substr_replace() replaces a specified portion of the target string with another string $myString = “It was the best of times, it was the worst of times,”; // Displays “It was the bananas” echo substr_replace( $myString, “bananas”, 11 ) . “ ”;

String Functions • strrev(string) • Returns the string in reverse order <?php $name = “Simon Stowart”; $strOutput = strrev($name); echo $name. “backwards is ”.$strOutput; ?>

String Functions • strtoupper(), strtolower(),ucfirst(),ucwords(); • Changes the case of string

<?php echo strtoupper("simon stowart")." ".strtolower("SIMON SOTWART"); echo " ".ucfirst("simon stowart")." ".ucwords("simon stowart");?> ?>

Formatting Functions printf() trim() removes white space from the beginning and end of a string ltrim() removes white space only from the beginning of a string rtrim() removes white space only from the end of a string

Array • Syntax • theArray = array(array1,array2… ,arrayN); • $arrColors = array(“Red”,”Blue”,”Yellow”,”White”);

<?php $arrColors = array(“Red”,”Blue”,”Yellow”,”White”); for ($ctr = 0; $ctr < 5; $ctr++) echo “”.$arrColors[$ctr].””; ?>

Array • Accessing array elements • Index or key

<?php $arrColors = array(0=>"Red",1=>"Blue",3=>"Yellow",5=>"White"); for ($ctr = 0; $ctr < 6; $ctr++) echo "".$arrColors[$ctr].""; ?>

foreach(array as value) statement <?php $arrColors = array(0=>"Red",1=>"Blue",3=>"Yellow",5=>"White"); $ctr =0; foreach ($arrColors as $strColor) { echo "".$ctr ." " .$strColor.""; $ctr++; } ?>

Arrays • Nonmerical keys <?php $arrColors = array("red"=>"Red","blue"=>"Blue","yello"=>"Yellow","white"=>"White"); foreach ($arrColors as $strkey => $strColor) echo "".$strkey ." : " .$strColor.""; ?>

Multi-dimensional array <?php $arrCars = array (array("Fords","Mazda","Toyota"), array("Blue","Red","Green"), array(1,2,4)); for ($ctr = 0; $ctr <3; $ctr++){ $makar = $arrCars[0][$ctr]; $color = $arrCars[1][$ctr]; $qty = $arrCars[2][$ctr]; echo " Maka: ".$maker." Color: ".$color. " Quantity: ".$qty .""; } ?>

Counting array elements $size = count(array)

Creating Stack • array_pop(array) • array_push(array,element)

Example <?php $arrColor = array("Red","Blue"); print_r($arrColor); $strColor = array_pop($arrColor); echo " Deleted color: ".$strColor." "; print_r($arrColor); array_push($arrColor,"Green"); echo " "; print_r($arrColor); ?>

Explode • Array = explode(separator, string); • the first string indicating the what characters will be use to search the string to separate it into individual array elements • The second parameter is the string itself

<?php $pizza = "piece1 piece2 piece3 piece4 piece5 piece6"; $pieces = explode(" ", $pizza); print_r($pieces); ?>

Implode • String = implode(separator, array); • The first string indicating what characters it will use to separate each element and the second is an array

<?php $array = array('lastname', 'email', 'phone'); $comma_separated = implode(",", $array); echo $comma_separated; // lastname,email,phone ?>

Using arrays in forms <?php $arrNames = array("Simon","Liz","Gemma","Hayley"); $strNames = implode("|",$arrNames); ?> <html> <body> <form method = "post" action="display.php"> <input type = "hidden" name="strNames" value =" <?php echo $strNames; ?>"> <input type = "text" name="names" maxlength="50" > <input type = "submit" name="submit" value="click"> </form> </body> </html>

<?php if(isset($_POST['submit'])){ echo " The array contains: "; $strNames = $_POST['strNames']."|".$_POST['names']; $arrNames = explode("|",$strNames); foreach($arrNames as $key => $value) echo "[". $key ."]".$value .""; } ?>

Strings and Arrays