getting-started-with-php
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June 20th 2015
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Created by Juan Manuel Torres / @onema
Born and raised in Bogotá Colombia
Software Engineer
MS Computer Science SDSU, 6+ years of experience
Started using PHP in 2000
Started programming in 1999
If we have time
What is GitHub?
Computer programs are collections of instructions that tell a computer how to interact with the user, the computer hardware or process data [1]
PHP (recursive acronym for PHP: Hypertext Preprocessor) is a widely-used open source general-purpose scripting language that is especially suited for web development [2]
Unlike other scripting languages that run directly in your computer, PHP will almost always run on a server.
"Hello, World!"
The "Hello, World!" program is the simplest program you can write in any programming language. All it does is output "Hello, World!" [3]
"Hello, World!"
<?php
// A simple web site in Cloud9 that runs through Apache ...
// THESE ARE COMMENTS AND WILL BE IGNORED BY PHP
/*
USE THE "/*" FOR
MULTILINE COMMENTS
*/
print 'Hello world from Cloud9!';
?>With our "php-intro-workshop" project there is a sample hello-world.php file
PHP Open tag: tells the computer where the php program starts
PHP only files do not require a closing php tag
A variable is a storage location associated with a name. Variables contain an unknown quantity or information called value [4]
<?php
// 01.simple_variable.php
$name = 'Juan';
$x = 30;
$y = 1.123;
// print the values below
print "";<?php
// 02.hello_name.php
$name = 'Juan';
print "Hello, $name!";
/**
* This will output:
* Hello, Juan!
*/A Data Type Is classification identifying one of various types of data [6]
PHP Defines eight data types [7]
<?php
// 03.data_types.php
print gettype(true) . PHP_EOL; // bolean
print gettype(12345) . PHP_EOL; // integer
print gettype(1.2345) . PHP_EOL; // double
print gettype("Hello") . PHP_EOL; // string
print gettype([1, 2, 3]) . PHP_EOL; // array
print gettype(new stdClass()) . PHP_EOL; // object
print gettype(null) . PHP_EOL; // NULL
PHP_EOL is a constant that represents the "End Of Line" symbol.
An operator in a programming language is a symbol that tells the [computer] to perform specific mathematical, relational or logical operation and produce final result. [8]
An operator is something that takes one or more values (or expressions, in programming jargon) and yields another value. [9]
| -$a | Negation | Opposite of $a. |
| $a + $b | Addition | Sum of $a and $b. |
| $a - $b | Subtraction | Difference of $a and $b. |
| $a * $b | Multiplication | Product of $a and $b. |
| $a / $b | Division | Quotient of $a and $b. |
| $a % $b | Modulus | Remainder of $a divided by $b. |
| $a ** $b | Exponentiation | Result of raising $a to the $b'th power. |
<?php
// 04.assignment_operator.php
$a = 1;
$b = 2;
$three = $a + $b;
print $three;
The assignment operator "=" is used to assign a value to a variable. It is not used to compare!
| $a == $b | Equal | TRUE if $a is equal to $b |
| $a === $b | Identical | TRUE if $a is equal to $b |
| $a != $b | Not equal | TRUE if $a is not equal to $b |
| $a !== $b | Not identical | TRUE if $a is not equal to $b |
| $a < $b | Less than | TRUE if $a is strictly less than $b . |
| $a > $b | Greater than | TRUE if $a is strictly greater than $b . |
| $a <= $b | Less than or equal to | TRUE if $a is less than or equal to $b . |
| $a >= $b | Greater than or equal to | TRUE if $a is greater than or equal to $b . |
<?php
// 05.comparison_operators.php
var_dump(1 == 2); // FALSE
var_dump(1 < 2); // TRUE
var_dump(1 <= 2); // TRUE
var_dump(2 > 2); // FALSE
var_dump(2 >= 2); // TRUE
var_dump(1 == true); // TRUE - same as (bool)1 == TRUE
var_dump(1 === true); // FALSE - same as (int)1 === FALSE
var_dump(0 == false); // TRUE - same as (bool)0 == FALSE
var_dump(0 === false); // FALSE - same as (int)0 === FALSEThe assignment operator "=" is used to assign a value to a variable. It is not used to compare!
Write a program that does the following:
An array in PHP is an ordered map.
A map is a type that associates values to keys [10]
Think of arrays as dictionaries or directories. The names in the directory are keys that help you look up information faster, values.
In an array the key is used to quickly look up for a value.
<?php
// 06.arrays.php
$array = array(
"foo" => "BAR",
"bar" => "FOO",
);
print $array['foo']; // bar
// as of PHP 5.4
$array = [
"new" => "array",
"syntax" => "use this",
];
print $array['syntax']; // use this
<?php
// 06.arrays.php continued
// if arrays are used without a key,
// zero indexed numeric values are
// assigned to them.
$array = ['apple', 'orange', 'banana'];
print $array[0]; // apple
print $array[1]; // orange
print $array[2]; // banana
<?php
// 06.arrays.php
$array = array(
"key" => "value",
1 => 1234,
"multi" => array(
"another key" => "Another Value"
)
);
It is possible to have an array of arrays
Think of an array as a specialized way of organizing and storing data [11].
PHP offers a wide range of functions to help you deal with arrays
<?php
//07.arrays_menu.php
$menu = [
'shake' => [
'vanilla ice cream',
'milk'
],
'tiramisu' => [
'instant-espresso powder',
'sugar',
'4 large egg',
'heavy cream'
]
'burger' => [
'beef patty',
'lettuce',
'tomatoes',
'buns'
],
];
ksort($menu);
print_r($menu);
So far we have created programs that have no logic, they follow a straight line.
Control Structures are used to build logic into our programs.
PHP supports several control structures but we will only look into the following:
If is a condition to check if something is true
<?php
// 08.if_statements.php
$number = 1;
if ($number === 1) {
print "The number variable is equals to one.";
}
$string = "Foo Bar";
if (strpos($string, "Foo") !== false) {
print "The string '$string' contains the word 'Foo'";
}
If you want to take an action If a condition is not met, use the else statement
<?php
// 09.else_statements.php
$number = 4;
if ($number === 1) {
print "The number variable is equal to one.";
} else {
print "The number variable IS NOT equal to one.";
}
$string = "Lala Bar";
if (strpos($string, "Foo") !== false) {
print "The string '$string' contains the word 'Foo'";
} else {
print "The word 'Foo' WAS NOT found in the string '$string'";
}
It is a combination of else and if. It is used to link multiple conditions.
<?php
// 10.elseif_statements.php
$number = 4;
if ($number === 1) {
print "The number variable is equal to one.";
} elseif ($number === 2) {
print "The number variable is equal to two.";
} elseif ($number === 3) {
print "The number variable is equal to three.";
} else {
print "I give up I don't know what the number is :(";
}
A loop allows us to repeat a piece of code many times.
Each time we loop we can make small changes to our program in order to get a desired output.
Imagine you want to print all the numbers from 1 to 10
<?php
// 11.for_loops.php
// with loops
for($i = 1; $i <= 10; $i++) {
print "I'm using a loop, my current count is $i";
}<?php
// 11.for_loops.php
// old way
print 1;
print 2;
// ...
print 10;
Expression 1 is executed once at the beginning of the loop
Expression 2 is evaluated on each iteration. The loop continues as long as the expression is true
Expression 3 is evaluated at the end of each iteration
<?php
// 12.for_loops_fib.php
$fib = [1, 2, 3, 5, 8, 13, 21, 34, 55, 89];
$size = sizeof($fib);
for($i = 0; $i < $size; $i++) {
print $fib[$i];
}
// We can also create this same series
// using simple math.
$a = 1;
$b = 2;
print $a;
print $b;
for($i = 0; $i < $size-2; $i++) {
$newB = $a+$b;
$a = $b;
$b = $newB;
print $newB;
}
<?php
// 13.foreach_loops_fib.php
$fib = [1, 2, 3, 5, 8, 13, 21, 34, 55, 89];
foreach($fib as $number) {
print $number;
}Foreach loops are meant to iterate over arrays or collections of objects
$numeros = ['uno' => 1, 'dos' => 2, 'tres' => 3];
// You can also get the key of the array
foreach ($numeros as $key => $value) {
print "The key of the current 'numero' is $key and the value is $value";
}Open the website directory. In there you will find several files. You only need to modify fibonacci.php and time.php
Open in the browser index.html
This file contains further information about this exercise
This website has a simple snipet of code written in JavaScript that will call two php files: time.php and fibonacci.php. You do not have to modify this file, just the PHP files.
Modify the time.php file to print the current time. Use the PHP Date Documentation to aid you with this task.
Modify the fibonacci.php file to print a json encoded array with the current number and the previous number in the series up to 200 K, after that reset the series and start all over again. Use the PHP json_encode Documentation to print a json encoded array. You will find each number that you need in the super global $_GET['fib_1'] and $_GET['fib_2']
Juan Manuel Torres | @onema