How to convert uint8 Array to base64 Encoded String?
All solutions already proposed have severe problems. Some solutions fail to work on large arrays, some provide wrong output, some throw an error on btoa call if an intermediate string contains multibyte characters, some consume more memory than needed.
So I implemented a direct conversion function which just works regardless of the input. It converts about 5 million bytes per second on my machine.
https://gist.github.com/enepomnyaschih/72c423f727d395eeaa09697058238727
/*MIT LicenseCopyright (c) 2020 Egor NepomnyaschihPermission is hereby granted, free of charge, to any person obtaining a copyof this software and associated documentation files (the "Software"), to dealin the Software without restriction, including without limitation the rightsto use, copy, modify, merge, publish, distribute, sublicense, and/or sellcopies of the Software, and to permit persons to whom the Software isfurnished to do so, subject to the following conditions:The above copyright notice and this permission notice shall be included in allcopies or substantial portions of the Software.THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS ORIMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THEAUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHERLIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THESOFTWARE.*/
/*// This constant can also be computed with the following algorithm:const base64abc = [], A = "A".charCodeAt(0), a = "a".charCodeAt(0), n = "0".charCodeAt(0);for (let i = 0; i < 26; ++i) { base64abc.push(String.fromCharCode(A + i));}for (let i = 0; i < 26; ++i) { base64abc.push(String.fromCharCode(a + i));}for (let i = 0; i < 10; ++i) { base64abc.push(String.fromCharCode(n + i));}base64abc.push("+");base64abc.push("/");*/const base64abc = [ "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "+", "/"];
/*// This constant can also be computed with the following algorithm:const l = 256, base64codes = new Uint8Array(l);for (let i = 0; i < l; ++i) { base64codes[i] = 255; // invalid character}base64abc.forEach((char, index) => { base64codes[char.charCodeAt(0)] = index;});base64codes["=".charCodeAt(0)] = 0; // ignored anyway, so we just need to prevent an error*/const base64codes = [ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 0, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51];
function getBase64Code(charCode) { if (charCode >= base64codes.length) { throw new Error("Unable to parse base64 string."); } const code = base64codes[charCode]; if (code === 255) { throw new Error("Unable to parse base64 string."); } return code;}
export function bytesToBase64(bytes) { let result = '', i, l = bytes.length; for (i = 2; i < l; i += 3) { result += base64abc[bytes[i - 2] >> 2]; result += base64abc[((bytes[i - 2] & 0x03) << 4) | (bytes[i - 1] >> 4)]; result += base64abc[((bytes[i - 1] & 0x0F) << 2) | (bytes[i] >> 6)]; result += base64abc[bytes[i] & 0x3F]; } if (i === l + 1) { // 1 octet yet to write result += base64abc[bytes[i - 2] >> 2]; result += base64abc[(bytes[i - 2] & 0x03) << 4]; result += "=="; } if (i === l) { // 2 octets yet to write result += base64abc[bytes[i - 2] >> 2]; result += base64abc[((bytes[i - 2] & 0x03) << 4) | (bytes[i - 1] >> 4)]; result += base64abc[(bytes[i - 1] & 0x0F) << 2]; result += "="; } return result;}
export function base64ToBytes(str) { if (str.length % 4 !== 0) { throw new Error("Unable to parse base64 string."); } const index = str.indexOf("="); if (index !== -1 && index < str.length - 2) { throw new Error("Unable to parse base64 string."); } let missingOctets = str.endsWith("==") ? 2 : str.endsWith("=") ? 1 : 0, n = str.length, result = new Uint8Array(3 * (n / 4)), buffer; for (let i = 0, j = 0; i < n; i += 4, j += 3) { buffer = getBase64Code(str.charCodeAt(i)) << 18 | getBase64Code(str.charCodeAt(i + 1)) << 12 | getBase64Code(str.charCodeAt(i + 2)) << 6 | getBase64Code(str.charCodeAt(i + 3)); result[j] = buffer >> 16; result[j + 1] = (buffer >> 8) & 0xFF; result[j + 2] = buffer & 0xFF; } return result.subarray(0, result.length - missingOctets);}
export function base64encode(str, encoder = new TextEncoder()) { return bytesToBase64(encoder.encode(str));}
export function base64decode(str, decoder = new TextDecoder()) { return decoder.decode(base64ToBytes(str));}
how to convert byte array to base64 encoded format?
Your file is a correct ASCII text file with content [\x58595a5052415445454b3123473b4c534e44204e474f49574853474849444748445348474d70253335]
literally.
That you get this content when you download it is perfectly fine, since it's what this file's content is.
What you want is to parse that content from the Hex representation they used to an actual ArrayBuffer to finally read that again as UTF-8 text (or any encoding respecting ASCII).
This has to be done after you do download the file and read it as text.
You first extract the actual bytes sequence as Hex from that [\x
- ]
wrapper, then you split the resulting string at every two chars to get hex values of every bytes, and finally you parse it into an Uint8Array to get back the original data:
// for StackSnippet we need to hardcode the response
// OP would have to make its request return that string
const response = { data: String.raw`[\x58595a5052415445454b3123473b4c534e44204e474f49574853474849444748445348474d70253335]` };
// .then( (response) => {
const encoded_text = response.data;
// remove leading "[\x" and final "]"
const encoded_data = encoded_text.slice( 3, -1 );
// split at every two chars, so we can get 0xNN, 0xNN
const hex_bytes = encoded_data.match( /.{2}/g );
// as numbers (0 - 255)
const num_bytes = hex_bytes.map( (hex) => parseInt( hex, 16 ) );
// wrap in an Uint8Array
const view = new Uint8Array( num_bytes );
// from there you can generate the Blob to save on disk
download( new Blob( [ view ] ), "file.txt" );
// but if you want to read it as UTF-8 text, you can:
const as_text = new TextDecoder().decode( view );
console.log( as_text );
// } );
function download( blob, filename ) {
const anchor = document.createElement( "a" );
anchor.href = URL.createObjectURL( blob );
anchor.download = filename;
anchor.textContent = "click to download";
document.body.append( anchor );
}
UInt8 Array to Base64 String Swift (Java Example Included)
Assuming that what you are truly looking for is a way to convert strings to and from Base64, here's a simple way to do that:
import Foundation
extension String {
func UTF8toBase64() -> String {
let data = self.dataUsingEncoding(NSUTF8StringEncoding)
return data?.base64EncodedStringWithOptions([]) ?? ""
}
func Base64toUTF8() -> String {
let data = NSData.init(base64EncodedString: self, options: []) ?? NSData()
return String(data: data, encoding: NSUTF8StringEncoding) ?? ""
}
}
let string = "Test"
let string64 = string.UTF8toBase64() // => "VGVzdA=="
let string2 = string64.Base64toUTF8() // => "Test
This, of course, assumes UTF-8 all the way through, you might want to allow other encodings.
How to convert a string to base64 encoding using byte array in JavaScript?
Your problem is caused by the following:
btoa()
is using ASCII encodingguid.ToByteArray();
does not use ASCII encoding
If you modify your C# code like this:
String str = "BBFDC43D-4890-4558-BB89-50D802014A97";
//Guid guid = new Guid(str);
//Console.WriteLine(guid);
// bbfdc43d-4890-4558-bb89-50d802014a97
//Byte[] bytes = guid.ToByteArray();
byte[] bytes = System.Text.Encoding.ASCII.GetBytes(str);
//Console.WriteLine(bytes); // System.Byte[]
String s = Convert.ToBase64String(bytes, Base64FormattingOptions.InsertLineBreaks);
Console.WriteLine(s);
You will get the following output:
QkJGREM0M0QtNDg5MC00NTU4LUJCODktNTBEODAyMDE0QTk3
Which will be the same string as the one returned from the btoa()
function:
var rawString = "BBFDC43D-4890-4558-BB89-50D802014A97";
var b64encoded = btoa(rawString);
console.log(b64encoded);
Output:
QkJGREM0M0QtNDg5MC00NTU4LUJCODktNTBEODAyMDE0QTk3
UPDATE - Since you can't modify the C# code
You should adapt your Javascript code by combining Piotr's answer and this SO answer
function guidToBytes(guid) {
var bytes = [];
guid.split('-').map((number, index) => {
var bytesInChar = index < 3 ? number.match(/.{1,2}/g).reverse() : number.match(/.{1,2}/g);
bytesInChar.map((byte) => { bytes.push(parseInt(byte, 16)); })
});
return bytes;
}
function arrayBufferToBase64(buffer) {
var binary = '';
var bytes = new Uint8Array(buffer);
var len = bytes.byteLength;
for (var i = 0; i < len; i++) {
binary += String.fromCharCode(bytes[i]);
}
return btoa(binary);
}
var str = "BBFDC43D-4890-4558-BB89-50D802014A97";
var guidBytes = guidToBytes(str);
var b64encoded = arrayBufferToBase64(guidBytes);
console.log(b64encoded);
Output:
PcT9u5BIWEW7iVDYAgFKlw==
How to convert unsigned byte array to base64 string in ctypes
Try this:
import ctypes
import base64
image = (ctypes.c_ubyte * s.dwDataLen)()
ctypes.memmove(image, s.pBuffer, s.dwDataLen)
# Convert the image to an array of bytes
buffer = bytearray(image)
encoded = base64.encodebytes(buffer)
If you are using base64.b64encode
, you should be able to pass image
to it:
import ctypes
import base64
image = (ctypes.c_ubyte * s.dwDataLen)()
ctypes.memmove(image, s.pBuffer, s.dwDataLen)
encoded = base64.b64encode(image)
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