40

How can I read the bytes of a String in dart? in Java it is possible through the String method getBytes().

See example

Miguel Ruivo
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gyorgio88
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4 Answers4

82
import 'dart:convert';

String foo = 'Hello world';
List<int> bytes = utf8.encode(foo);
print(bytes);

Output: [72, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]

Also, if you want to convert back:

String bar = utf8.decode(bytes);
Miguel Ruivo
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16

There is a codeUnits getter that returns UTF-16 

String foo = 'Hello world';
List<int> bytes = foo.codeUnits;
print(bytes);

[72, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]

and runes that returns Unicode code-points

String foo = 'Hello world';
// Runes runes = foo.runes;
// or
Iterable<int> bytes = foo.runes;
print(bytes.toList());

[72, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]

Günter Zöchbauer
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  • Yup the differences will only show when you use multi-byte characters, but I don't know your use case and I don't know what `getBytes()` does exactly. I thought alternative options would at least be interesting to know ;-) – Günter Zöchbauer Feb 23 '19 at 18:03
  • I just tried utf8.encode() of the package 'dart:convert' and I get the desired result..E.G: print("哔".runes.length) return -> 1 byte, instead print(utf8.encode("哔").length) return -> 3 byte – gyorgio88 Feb 23 '19 at 18:10
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    `utf8.encode()` returns individual bytes `[229, 147, 148]`, my variants return `[21716]`. Is this what you actually wanted because you accepted my answer? – Günter Zöchbauer Feb 23 '19 at 18:17
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    sorry, i'm wrong ... yours is a alternative options for other contexts. thanks :) – gyorgio88 Feb 23 '19 at 18:21
5

If you're looking for bytes in the form of Uint8List, use

import 'dart:convert';
import 'dart:typed_data';

var string = 'foo';
Uint8List.fromList(utf8.encode(string));
Chuck Batson
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2

For images they might be base64 encoded, use

Image.memory(base64.decode('base64EncodedImageString')),

import function from

import 'dart:convert';
A.Mushate
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