Crate numtoa

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Expand description

The standard library provides a convenient method of converting numbers into strings, but these strings are heap-allocated. If you have an application which needs to convert large volumes of numbers into strings, but don’t want to pay the price of heap allocation, this crate provides an efficient no_std-compatible method of heaplessly converting numbers into their string representations, storing the representation within a reusable byte array.

In addition to supporting the standard base 10 conversion, this implementation allows you to select the base of your choice. Therefore, if you want a binary representation, set the base to 2. If you want hexadecimal, set the base to 16.

Convenience Example

use numtoa::NumToA;

let mut buf = [0u8; 20];
let mut string = String::new();

for number in (1..10) {
    string.push_str(number.numtoa_str(10, &mut buf));
    string.push('\n');
}

println!("{}", string);

Base 10 Example

use numtoa::NumToA;
use std::io::{self, Write};

let stdout = io::stdout();
let mut stdout = stdout.lock();
let mut buffer = [0u8; 20];

let number: u32 = 162392;
let mut start_indice = number.numtoa(10, &mut buffer);
let _ = stdout.write(&buffer[start_indice..]);
let _ = stdout.write(b"\n");
assert_eq!(&buffer[start_indice..], b"162392");

let other_number: i32 = -6235;
start_indice = other_number.numtoa(10, &mut buffer);
let _ = stdout.write(&buffer[start_indice..]);
let _ = stdout.write(b"\n");
assert_eq!(&buffer[start_indice..], b"-6235");

let other_number: i8 = -128;
start_indice = other_number.numtoa(10, &mut buffer);
let _ = stdout.write(&buffer[start_indice..]);
let _ = stdout.write(b"\n");
assert_eq!(&buffer[start_indice..], b"-128");

let other_number: i8 = 53;
start_indice = other_number.numtoa(10, &mut buffer);
let _ = stdout.write(&buffer[start_indice..]);
let _ = stdout.write(b"\n");
assert_eq!(&buffer[start_indice..], b"53");

let other_number: i16 = -256;
start_indice = other_number.numtoa(10, &mut buffer);
let _ = stdout.write(&buffer[start_indice..]);
let _ = stdout.write(b"\n");
assert_eq!(&buffer[start_indice..], b"-256");

let other_number: i16 = -32768;
start_indice = other_number.numtoa(10, &mut buffer);
let _ = stdout.write(&buffer[start_indice..]);
let _ = stdout.write(b"\n");
assert_eq!(&buffer[start_indice..], b"-32768");

let large_num: u64 = 35320842;
start_indice = large_num.numtoa(10, &mut buffer);
let _ = stdout.write(&buffer[start_indice..]);
let _ = stdout.write(b"\n");
assert_eq!(&buffer[start_indice..], b"35320842");

let max_u64: u64 = 18446744073709551615;
start_indice = max_u64.numtoa(10, &mut buffer);
let _ = stdout.write(&buffer[start_indice..]);
let _ = stdout.write(b"\n");
assert_eq!(&buffer[start_indice..], b"18446744073709551615");

Traits

Converts a number into a string representation, storing the conversion into a mutable byte slice.