How do I print a Rust floating-point number with all available precision?

Question

I am implementing the CORDIC algorithm for the sin trigonometric function. In order to do this, I need to hardcode/calculate a bunch of arctangent values. Right

Answer 1

This answer was written for Rust 0.12.0 and doesn't apply to Rust 1.x.

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You can use the to_string function in std::f32 (not to be confused with the to_string method):

fn main() {
    println!("{}", std::f32::to_string(unsafe { std::mem::transmute::(1) }));
    println!("{}", std::f32::to_string(unsafe { std::mem::transmute::(16) }));
    println!("{}", std::f32::to_string(std::f32::MIN_POS_VALUE));
    println!("{}", std::f32::to_string(std::f32::MAX_VALUE));
    println!("{}", std::f32::to_string(std::f32::consts::PI));
}

Output:

0.00000000000000000000000000000000000000000000140129852294921875
0.000000000000000000000000000000000000000000022420775890350341796875
0.000000000000000000000000000000000000011754944324493408203125
340282368002860660002286082464244022240
3.1415927410125732421875