{"id":2019,"date":"2021-06-27T03:15:50","date_gmt":"2021-06-27T03:15:50","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=2019"},"modified":"2025-04-05T14:40:28","modified_gmt":"2025-04-05T14:40:28","slug":"php-type-juggling","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/php-type-juggling\/","title":{"rendered":"PHP Type Juggling"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about PHP type juggling and how it works.<\/p>\n\n\n\n

Introduction to PHP type juggling #<\/a><\/h2>\n\n\n\n

PHP is a loosely typed programming language. It means that when you define a variable<\/a>, you don’t need to declare its type<\/a>. Internally, PHP will determine the type by the context in which you use the variable.<\/p>\n\n\n\n

For example, if you assign a string to a variable, its type will be the string:<\/p>\n\n\n

<?php<\/span>\n\n$my_var = 'PHP'<\/span>; \/\/ a string<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
If you assign an integer to the same variable, and its type will be the integer:<\/p>\n\n\n
<?php<\/span>\n\n$my_var = 'PHP'<\/span>; \/\/ a string<\/span>\n$my_var = 100<\/span>; \/\/ an integer<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
PHP has a feature called type juggling. It means that when comparing variables of different types, PHP will convert them to the common, comparable type. For example:<\/p>\n\n\n
<?php<\/span>\n$qty = 20<\/span>;\nif<\/span>($qty == '20'<\/span>) {\n    echo<\/span> 'Equal'<\/span>;\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Equal<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Because of type juggling, PHP converts the string '20'<\/code> to an integer (20<\/code>) and compares it with the $qty<\/code> variable. The result is true<\/code>. Therefore, you’ll see the message Equal<\/code> in the output.<\/p>\n\n\n\n
The type juggling also works in arithmetic operations for variables of different types. The following example illustrates how the type juggling works in an arithmetic operation:<\/p>\n\n\n
<?php<\/span>\n\n$total = 100<\/span>;\n$qty = \"20\"<\/span>;\n$total = $total + $qty;\n\necho<\/span> $total; \/\/ 120<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The type of $total<\/code> is an integer, whereas the $qty<\/code> is a string. To calculate the sum, PHP first converts the value of the $qty variable to an integer. The result is an integer.<\/p>\n\n\n\n
Consider the following example:<\/p>\n\n\n
<?php<\/span>\n\n$total = 100<\/span>;\n$qty = \"20 pieces\"<\/span>;\n$total = $total + $qty;\n\necho<\/span> $total; \/\/ 120<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, PHP casts the string “20 pieces” as an integer 20 before calculating the sum.<\/p>\n\n\n\n
Note that PHP also throws a warning message:<\/p>\n\n\n
A non-numeric value encountered<\/code><\/span><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
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  • PHP is a loosely typed language. PHP determines the variable type based on the value.<\/li>\n\n\n\n
  • When comparing values of different types, PHP implicitly converts them to the same comparable type.<\/li>\n<\/ul>\n
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