The Spaceship Operator in PHP

surrounded by spaceship icons
By the Dev Team in Development

What is the spaceship operator?

Well, let’s start with what an operator is, just to be clear. An operator is any symbol used to “operate” on a variable. The spaceship operator in particular is part of a subset of operators called “comparison operators” which are used, you guessed it, to compare two values against each other (think equals [=], greater than [>], or less than [<], etc.).

So what is it?

Well firstly, it looks like this: <=>

See! It’s a cute little spaceship.

And what it does is when you compare two values it gives you one of three results: -1, 0, or 1. In other words, it’s equivalent to this:

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if ($a == $b) {
    return 0; 
}
if ($a > $b) {
    return -1; 
}
if ($a < $b) {
    return 1; 
}

How is the spaceship operator useful?

The spaceship operator is most useful in sorting functions. Because it uses standard PHP comparison rules you can use it to weigh variables of just about any type. Unlike, say, the strcmp function, you aren’t just limited to strings. You can compare just about anything. From strings to numbers to datetime objects.

Conclusion

In summary, the spaceship operator offers a concise and elegant way to perform three-way comparisons in PHP. Whether you are building custom sorting algorithms or streamlining simple conditional logic, it remains a highly valuable addition to any PHP developer’s toolkit.