Character Sets

Percent-encode a string

Encode an input string withpercent-encoding using theutf8_percent_encode function from thepercent-encoding crate. Then decodeusing thepercent_decode function.

use percent_encoding::{utf8_percent_encode, percent_decode, AsciiSet, CONTROLS};use std::str::Utf8Error;/// https://url.spec.whatwg.org/#fragment-percent-encode-setconst FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`');fn main() -> Result<(), Utf8Error> {    let input = "confident, productive systems programming";    let iter = utf8_percent_encode(input, FRAGMENT);    let encoded: String = iter.collect();    assert_eq!(encoded, "confident,%20productive%20systems%20programming");    let iter = percent_decode(encoded.as_bytes());    let decoded = iter.decode_utf8()?;    assert_eq!(decoded, "confident, productive systems programming");    Ok(())}

The encode set defines which bytes (in addition to non-ASCII and controls) needto be percent-encoded. The choice of this set depends on context. For example,url encodes? in a URL path but not in a query string.

The return value of encoding is an iterator of&str slices which collect intoaString.

Encode a string as application/x-www-form-urlencoded

Encodes a string intoapplication/x-www-form-urlencoded syntaxusing theform_urlencoded::byte_serialize and subsequentlydecodes it withform_urlencoded::parse. Both functions return iteratorsthat collect into aString.

use url::form_urlencoded::{byte_serialize, parse};fn main() {    let urlencoded: String = byte_serialize("What is ❤?".as_bytes()).collect();    assert_eq!(urlencoded, "What+is+%E2%9D%A4%3F");    println!("urlencoded:'{}'", urlencoded);    let decoded: String = parse(urlencoded.as_bytes())        .map(|(key, val)| [key, val].concat())        .collect();    assert_eq!(decoded, "What is ❤?");    println!("decoded:'{}'", decoded);}

Encode and decode hex

Thedata_encoding crate provides aHEXUPPER::encode method whichtakes a&[u8] and returns aString containing the hexadecimalrepresentation of the data.

Similarly, aHEXUPPER::decode method is provided which takes a&[u8] andreturns aVec<u8> if the input data is successfully decoded.

The example below converts&[u8] data to hexadecimal equivalent. Compares thisvalue to the expected value.

use data_encoding::{HEXUPPER, DecodeError};fn main() -> Result<(), DecodeError> {    let original = b"The quick brown fox jumps over the lazy dog.";    let expected = "54686520717569636B2062726F776E20666F78206A756D7073206F76\        657220746865206C617A7920646F672E";    let encoded = HEXUPPER.encode(original);    assert_eq!(encoded, expected);    let decoded = HEXUPPER.decode(&encoded.into_bytes())?;    assert_eq!(&decoded[..], &original[..]);    Ok(())}

Encode and decode base64

Encodes byte slice intobase64 String usingencodeand decodes it withdecode.

use anyhow::Result;use std::str;use base64::{encode, decode};fn main() -> Result<()> {    let hello = b"hello rustaceans";    let encoded = encode(hello);    let decoded = decode(&encoded)?;    println!("origin: {}", str::from_utf8(hello)?);    println!("base64 encoded: {}", encoded);    println!("back to origin: {}", str::from_utf8(&decoded)?);    Ok(())}