UNDERSTANDING VARIABLES AS A BEGINNER IN PHP
Published: 2022-11-26 09:07:15

**Introduction**

​​**What is a Variable?**
​​
​​Variables are containers or placeholders which are used to store data, and that data can be used by assigning a name to the variable. Variables are very useful and powerful, it is used in all kinds of programming languages. 
​​
​​**VARIABLES IN PHP**
​​
​​In PHP, a variable is declared with the dollar sign **$**, followed by the name of the variable: 
​​
​​**Example:**

```
​​<?php
​​$name = “Oswin”;
​​$number = 100;
​​echo $name;
​​echo $number
​​?>
```
​​

## ​​**Factors to consider before defining a variable**
​​
* The symbol **=** is an assignment operator used to assign the variable name or value.  

* Numbers In variables do not have or need quotes **“”** around them, quotes are used to identify strings. This is how PHP knows that it is a number. 

- The function **echo** is used to execute the value by using the variable name.
**echo $name;**
​​**echo $number;**

- You can choose to write variables however you wish, could be in upper cases or lowercases.
​​**$Number**
​​**$NUMBER**

​​Both variables above are acceptable but are different from each other. A value assigned to one cannot to called out by the other, why? Because variables are case sensitive. 
​​
​​For best results it is advisable to use all lowercase. If variable contains two words, then you can separate words with either an underscore **_** or an uppercase. 
​​ **$numerList = 100**
​​ **$number_list = 100**
​​ 
​​ 
​​ 

## **Rules for declaring PHP variable:**
- A variable must start with a dollar sign, **$** followed by the variable name.

- It contains only alpha-numeric characters and underscore.

- A variable cannot start with a number or special symbols, it must start with an alphabet or underscore **_**

- A variable name cannot contain any space. 

- PHP variables are case sensitive.
​​ 

## **CONCATENATION IN PHP**
Concatenation is basically a series of interconnected things, joining things together. 
​​
In PHP you can add two or more different variable values together using concatenation. 
​​It is done with the used of a dot (.)
​​

```
​​<?php
​​$name = “Edwin”;
​​$number = 100;
​​echo $name . $number;
​​?>
​​ 
​​RESULT :  Edwin100
​​
```
​​**note:** To create a space between two values, you use the quote symbol **“ “**
​​
​​

```
echo $name . “ “ . $number
​​
​​RESULT : Edwin 100
​​
```

## ​​**Things that can be assigned to variables in PHP**
​​
- We can assign html tags to variables 
​​    
```
$name = “<h1> HELLO </h1>”;
```
- We can assign images to variables 
​​
- We can assign many different data into a variable.

- Keep in mind that you can only assign one value at a time.
​​

## ​​**Declaring a text, integer, and float**
​​
​​Let's look at a PHP variable example that stores string, integer, and float values.
​​
​​**Example**
​​

```
<?php  
​​$str="hello there";  
​​$x=56;  
​​$y=56.6;  
​​echo "string is: $str <br/>";  
​​echo "integer is: $x <br/>";  
​​echo "float is: $y <br/>";  
​​?>  
```
​​
​​
**Output**
```
​​string is: hello there
​​integer is: 56
​​float is: 56.6 
​​
```
​​

## **​​Case Sensitivity** 
​​Variable names in PHP are case-sensitive. The term "color" is so distinct from the terms Color, COLOR, COLor, etc.
​​
​​**Example**
​​
```
<?php  
​​$color="green";  
​​echo "My pen is " . $color . "<br>";  
​​echo "My house is " . $COLOR . "<br>";  
​​echo "My boat is " . $coLOR . "<br>";  
​​?>  
```
​​ 
​​ 
​​**Output**
​​

```
My pen is green
​​Notice: Undefined variable: COLOR in C:\wamp\www\variable.php on line 4
​​My house is 
​​Notice: Undefined variable: coLOR in C:\wamp\www\variable.php on line 5
​​My boat is 
```
​​
​​

## ​​**Conclusion** 
​​Depending on its value, PHP automatically assigns a data type to the variable. Since the data types are not strictly defined, it is possible to add a string to an integer without running into problems.
​​