Simplified PHP

Simplified PHP

James Blanchette PhD

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copyright James Blanchette 2018

Published by Spangaloo Publishing

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Spangaloo Edition

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Contents

Preface

What is PHP

PHP Basics

IF ELSE ELSEIF

WHILE

DO WHILE

FOR NEXT

FOREACH

SWITCH

TRIM

STRINGS

str_replace

explode

String Change case strtolower() strtoupper() ucfirst() ucwords()

substr

strpos

strlen

strstr

ARRAYS

ISSET

COUNT

TIME

SESSIONS

MYSqli

MySqli Connect

Mysqli Query

Classes

Some simple rules

Reusable pages

Reusable code

Generic functions

HTML with PHP

CSS and PHP

Controlling User Input

Security

Harden Your PHP

Sessions

Website

Database

Building Websites

AJAX

Error Control

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Mysql Data Types

MYSQL Keywords and Reserved Words

List of Keywords PHP

String Functions List

Time Zone List

Date Format Characters List

Other Books

Preface

What this book is about, is not to teach you how to program in PHP but to show you more structured way to improve what you’re already doing by reusing code and building better functions that will be useful in the long term. Beyond that, working with code that is easily readable and understandable by just applying a few programming practices. This doesn’t produce the most efficient code but it does allow you to completely understand what you’ve written before, to easily make changes at any time.

Probably most importantly providing a different aspect to how you program.

It’s time to stop reinventing the wheel every time you have to build a new website. As well to provided list of commands that you are likely to use every day including how to use them and what the parameters mean.

What is PHP?

From the preface of the manual:

PHP is an HTML-embedded scripting language. Much of its syntax is borrowed from C, Java and Perl with a couple of unique PHP-specific features thrown in. The goal of the language is to allow web developers to write dynamically generated pages quickly.

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What does PHP stand for?

PHP stands for PHP: Hypertext Preprocessor. This confuses many people because the first word of the acronym is the acronym. This type of acronym is called a recursive acronym.

I’d like to start by explaining that PHP is an incredibly complex language, capable of most if not all the things that you would like it to do.

Everything from robust classes to give you object orientated programming, to simply displaying the date on a website. PHP can be utilized using Ajax for dynamic web development that encompasses both server-side and client-side.

Most problems stem from trying to fix code that you wrote six months ago. As you look at it is more difficult to glean any kind of reference to what you are thinking about at the time.

Embedding comments in your files is something that is not only helpful, it is absolutely necessary especially if you need to do some rewrites.

PHP is constantly evolving and as such various commands are either improved and changed or disregarded completely and no longer available.

Simplifying the writing of PHP, to make it easier to understand in the future is what we are going to be talking about. Simplifying the PHP does not make it as efficient as some more complicated versions of the code can be, however readability is what we’re after.

Bear in mind that simplifying PHP is not just about writing readable code, it’s about being able to reuse the code over and over again thus saving you time, energy and frustration.

PHP Basics

This chapter will outline some of the basics of PHP including some of the necessary commands and keywords that you will use it continuously throughout your PHP programming. You can skip this particular chapter if your are you familiar with most of the PHP concepts.

IF ELSE ELSEIF

The if construct or command is available in almost all programming languages. It allows for conditional execution of code. The IF structure itself is similar to that of C programming language.

The expression is evaluated to its boolean value and if the expression is true then the rest of the statement is executed, if it is false that everything gets ignored.

if (expr)

statement

if (condition) {

code to be executed if condition is true;

}

An example.

$t = date(H);

if ($t <= 20) {

echo Have a good day!;

}else{

echo Have a good night!;

}

By using the else command when the expression is false, we can still do something. It could be to generate an error or output something completely different.

ELSEIF

if (condition) {

code to be executed if this condition is true

} elseif (condition) {

code to be executed if this condition is true;

} else {

code to be executed if all conditions are false;

}

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if ( isset ($_SERVER[HTTP_X_FORWARDED])){

$testip = $_SERVER[HTTP_X_FORWARDED];

}elseif ( isset ($_SERVER[HTTP_FORWARDED_FOR])){

$testip = $_SERVER[HTTP_FORWARDED_FOR];

}elseif ( isset ($_SERVER[HTTP_FORWARDED])){

$testip = $_SERVER[HTTP_FORWARDED];

}elseif ( isset ($_SERVER[HTTP_X_FORWARDED])){

$testip = $_SERVER[HTTP_X_FORWARDED];

}else{

if ( isset ($_SERVER[REMOTE_ADDR])){

$testip = $_SERVER[REMOTE_ADDR];}

}

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The above code steps through a list of possibilities to grab the user’s IP address.

$t = date(H);

if ($t <= 10) {

echo Have a good morning!;

} elseif ($t <= 20) {

echo Have a good day!;

} else {

echo Have a good night!;

}

Special characters.

The IF statement generally uses two characters in determining whether a statement is true or not. If it is going to equal something then best practice suggest you use a double Equal sign ==. There are other characters involved and well as can be seen in the above code using the less than <= but also available is the greater than >=. Others are using both greater than and less than two equate to not equal <> as well this != also means not equal to.

There are other ways to express the same thing in a shorter version. Consider this.

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if ($condition) {

$result = 'foo'

} else {

$result = 'bar'

}

can also be expressed this way.

$result = $condition ? 'foo' : 'bar';

If this $condition evaluates to true, the lefthand operand will be assigned to $result. If the condition evaluates to false, the righthand will be used. As well you can use additional equations as part of a single if statement by using logical operators. You have and, or, XOR,&& || and ! Each performing its own way.

if (x==1 and y=2){

}

if (x==1 && y=2){

}

if (x==1 or y=2){

}

Special conditions also exist , using the triple equal is not the same as using a double equal

if($a == $b){

// do something

}

Equal true: if $a is equal to $b, after type juggling.

if($a === $b){

// do something

}

Identical true: if $a is equal to $b, and they are of the same type. So what that means is that if both are integers or perhaps floating-point as well as a string type they can be compared by their type to evaluate whether they’re true or not. If you mix an imager with a string and use the triple equal it will always be false.

WHILE

The while command is used in loops and will continue to loop as long as a given condition is true. It also follows a similar structure to the IF command.

while (expr)

statement

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The meaning of the while command is simple PHP will execute the necessary men's repeatedly as long as the while at expression evaluates to true. The value is checked at the beginning of the loop so even if the value changes during execution execution will not stop until the end of the iteration.

If the expression evaluates to false then the while command will not execute any code.

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$x = 1;

while ($x <= 10) {

echo $x++;

/* the printed value would be $x before the increment (post-increment) */

}

As well without curly braces.

$x = 1;

while ($x <= 10):

echo $x;

$x++;

endwhile;

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Database access heavily utilizes the while command as seen below.

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$querysub = select * from sometable order by rand() limit 5;

$resultSub = mysqli_query($con,$querysub) or die(mysqli_error($con)) ;

if(mysqli_num_rows($resultSub)>=1)

{

//$output[];