PHP Numeric Literal Separator

By Dillon Smart · · · 0 Comments

First introduced in PHP 7.4, the Numeric Literal Separator in PHP makes large integers within your code easy to read.

Naturally, we find it easier to read number which are grouped, for example, 1,650,000.

Using the numeric literal separator in PHP

Since PHP 7.4, we can now use numbers like this:

$number = 1_650_000;

echo $number; // 1650000

Adding an underscore between digits in a numeric literal will not change its value. The underscores are stripped out during the lexing stage, so the runtime is not affected.

I wrote an post which explains more about the Lexing stage in PHP.

var_dump(1_000_000); // int(1000000)

The numeric literal separator can be used with all numeric literal notations supported in PHP.

  • Float
  • Decimal
  • Hexadecimal
  • Binary
  • Octal

Restrictions with the numeric literal separator in PHP

The only restriction with the numeric literal separator is that each underscore must directly between wo digits.

Here is a list of examples which would throw a Parse error: syntax error.

100_;       // trailing
1__1;       // next to underscore
1_.0; 1._0; // next to decimal point
0x_123;     // next to x
0b_101;     // next to b
1_e2; 1e_2; // next to e

Learn about new features coming in PHP 8.3.


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