Difference Between PHP 5 and PHP 7

By Shahnail Khan Last updated : November 28, 2023

With each version release, PHP undergoes significant improvements in performance, security, and functionality. In this article, we'll explore the differences between PHP 5 and PHP 7. We will also know why upgrading to the latest version is the best choice for developers.

PHP 5: The Foundation

PHP 5, initially released on July 1, 2004, was an upgraded version of PHP 4, where Zend Engine II replaced the old Zend Engine 1.0.

Let's explore the key features of PHP 5:

  • Improved support for object-oriented programming
  • The PHP Data Objects (PDO) extension
  • Numerous performance enhancements
  • Rewritten XML functionality
  • Upgraded Zend Engine


Released in 2015, PHP was a new major PHP version with some advanced features. It introduced the

PHP next generation (phpng)

engine, which aims to improve performance and memory usage efficiency.

Let's take a closer look at the advancements brought by PHP 7:

  • PHP 7 makes error management better with modern exceptions.
  • You can now use operators like ->, [], (), {}, and :: more consistently with variables.
  • Old PHP 4-style constructors are phased out for clearer code.
  • The foreach loops work more predictably for better iteration.
  • Class constructors now use exceptions for consistent error handling.
  • Outdated server APIs (like the old mysql extension) are removed.
  • The list() operator no longer supports strings for simpler use.
  • Old delimiters <% and %> and <script language="php"> ... </script> are removed.
  • The switch statements can't have multiple default clauses now.
  • Hexadecimal number support in certain conversions is taken out.
  • Left-shift and right-shift operators now behave the same way across platforms.
  • Converting between floating-point numbers and integers is more consistent.
  • PHP 7 lets you declare the return type of functions.
  • Now you can use scalar types (integer, float, string, boolean) in parameters and return types.

Differences between PHP 5 and PHP 7

  1. One of the most significant improvements in PHP 7 is the performance boost. PHP 7 introduced the Zend Engine 3.0, which significantly enhances the execution speed of PHP code compared to PHP 5.
  2. PHP 7 introduced scalar-type declarations, allowing you to declare the expected data type for function parameters and return values. This includes types such as int, float, string, and bool. PHP 5 only supports type hints for classes and arrays.
  3. PHP 7 allows you to declare the expected return type of a function, providing better clarity. PHP 5 does not support return-type declarations.
  4. PHP 7 introduced the null coalescing operator (??), which simplifies the process of checking if a variable is set and not null. This operator was not available in PHP 5.
  5. PHP 7 introduced the spaceship operator (<=>), which is a combined comparison operator used for comparing two expressions. It returns -1, 0, or 1, indicating whether the left operand is less than, equal to, or greater than the right operand. PHP 5 does not have this operator.
  6. PHP 7 introduced two new classes for handling errors and exceptions: Error and Exception. This allows for better handling of different types of errors. In PHP 5, exception handling was possible, but it was not as standardized.
  7. PHP 7 introduced the ability to import multiple classes from the same namespace in a single-use statement. In PHP 5, each class needed its use statement.
  8. While PHP 5 had some support for 64-bit systems, PHP 7 provides better and more consistent support for 64-bit architectures.


1. Why upgrade to PHP 7 from PHP 5?

PHP 7 offers significant performance improvements, introduces new language features for better code quality, and ensures ongoing security support compared to the deprecated PHP 5.

2. What are the key features introduced in PHP 7?

PHP 7 introduces scalar type declarations, return type declarations, the null coalescing operator, the spaceship operator and consistent 64-bit support.

3. What is PHP 7 Null Coalescing Operator?

Let's understand this operator by a simple example.

$snack = $cookie?? $chocolate;

This line of code means that,

  • If there's a cookie ($cookie is not null), you get the cookie.
  • If there's no cookie (it's null), you accept the chocolate ($chocolate).


It's a quick and easy way to get what you want, whether it's a cookie or chocolate, without writing a bunch of lines of code to check if the cookie exists. In PHP 5, you would have had to write more lines to achieve the same result. So, the null coalescing operator in PHP 7 makes your code shorter.

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