I'm writing a Rust program that reads off of an I2C bus and saves the data. When I read the I2C bus, I get hex values like 0x11, 0x22, etc.
Right now, I can only handle this as a string and save it as is. Is there a way I can parse this into an integer? Is there any built in function for it?
In most cases, you want to parse more than one hex byte at once. In those cases, use the hex crate.
parse this into an integer
You want to use from_str_radix. It's implemented on the integer types.
use std::i64;
fn main() {
let z = i64::from_str_radix("1f", 16);
println!("{:?}", z);
}
If your strings actually have the 0x prefix, then you will need to skip over them. The best way to do that is via trim_start_matches or strip_prefix:
use std::i64;
fn main() {
let raw = "0x1f";
let without_prefix = raw.trim_start_matches("0x");
let z = i64::from_str_radix(without_prefix, 16);
println!("{:?}", z);
}
&raw[2..] is a substring of raw starting at the second byte of raw.
trim_start_matches removes the prefix repeatedly, so that would also parse 0x0x0x1f. You can use strip_prefix to remove only once, but will need to differentiate the two cases.strip_prefix was mentioned earlier, and actually isn't as much trouble to use as it might seem at a casual glance. It can be nested and does the expected thing. Playground Link
fn trimhex(s: &str) -> &str {
s.strip_prefix("0x").unwrap_or(s.strip_prefix("0X").unwrap_or(s))
}
fn main() {
println!("{}", trimhex("0123"));
println!("{}", trimhex("0x01"));
println!("{}", trimhex("0X23"));
// only the first leading 0[xX] is removed
println!("{}", trimhex("0x0x45"));
println!("{}", trimhex("0x0X67"));
println!("{}", trimhex("0X0x89"));
println!("{}", trimhex("0X0Xab"));
}
