Originally published on php2rust.dev — part of the PHP to Rust course. View this lesson on the original site.

Rust has two floating-point types: f32 and f64. PHP has a single float type (double precision).

Rust

fn main() {
    let x: f64 = 3.14;       // Default, double precision
    let y: f32 = 2.5_f32;    // Single precision

    let sum = x + y as f64;  // Must convert for mixed operations
    println!("sum = {}", sum);

    // Special values
    let inf = f64::INFINITY;
    let nan = f64::NAN;
    println!("inf = {}, nan = {}", inf, nan);
}

f64 is the default (like double in C).
f32 uses less memory, f64 is more precise.
Mixed arithmetic requires explicit conversion.

PHP

<?php
$x = 3.14;      // float (double precision)
$y = 2.5;

$sum = $x + $y;
echo "sum = $sum\n";

// PHP has is_finite(), is_infinite(), is_nan()
$inf = INF;
$nan = NAN;
var_dump(is_infinite($inf));  // true
var_dump(is_nan($nan));       // true

PHP uses 64-bit floats (IEEE 754 double). There is no single-precision type.

Comparison

Rust: f32 and f64; default is f64. Use suffix for literals: 2.0_f32.
PHP: Single float type (double precision).

References

What's next

Next: Booleans.

From PHP to Rust — Rust Syntax and Functions