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PHP Variables


A variable in PHP is a name of memory location that holds data. A variable is a temporary storage that is used to store data temporarily.

In PHP, a variable is declared using $ sign followed by variable name.

Syntax of declaring a variable in PHP is given below:

  1. $variablename=value;

PHP Variable: Declaring string, integer and float

Let’s see the example to store string, integer and float values in PHP variables.

File: variable1.php

  1. <?php
  2. $str=“hello string”;
  3. $x=200;
  4. $y=44.6;
  5. echo “string is: $str <br/>“;
  6. echo “integer is: $x <br/>“;
  7. echo “float is: $y <br/>“;
  8. ?>

Output:

string is: hello string
integer is: 200
float is: 44.6 

PHP Variable: Sum of two variables

File: variable2.php

  1. <?php
  2. $x=5;
  3. $y=6;
  4. $z=$x+$y;
  5. echo $z;
  6. ?>

Output:

11

PHP Variable: case sensitive

In PHP, variable names are case sensitive. So variable name “color” is different from Color, COLOR, COLor etc.

File: variable3.php

  1. <?php
  2. $color=“red”;
  3. echo “My car is ” . $color . “<br>“;
  4. echo “My house is ” . $COLOR . “<br>“;
  5. echo “My boat is ” . $coLOR . “<br>“;
  6. ?>

Output:

My car is red
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 

PHP Variable: Rules

PHP variables must start with letter or underscore only.

PHP variable can’t be start with numbers and special symbols.

File: variablevalid.php

  1. <?php
  2. $a=“hello”;//letter (valid)
  3. $_b=“hello”;//underscore (valid)
  4. echo “$a <br/> $_b”;
  5. ?>

Output:

hello 
hello

File: variableinvalid.php

  1. <?php
  2. $4c=“hello”;//number (invalid)
  3. $*d=“hello”;//special symbol (invalid)
  4. echo “$4c <br/> $*d”;
  5. ?>

Output:

Parse error: syntax error, unexpected '4' (T_LNUMBER), expecting variable (T_VARIABLE)
 or '$' in C:\wamp\www\variableinvalid.php on line 2

PHP: Loosely typed language

PHP is a loosely typed language, it means PHP automatically converts the variable to its correct data type.

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