I have two different list values i want get the corresponding one list between value to other list between values. Please look at the list below. Here i have 1st list value of 11 and 15 here i need to find the between values of 12, 13 and 15.
11 value =22
15 value =30
List<double> list1 =[11, 15];
List<double> list2 =[22, 30];
If I understand correct you need the interpolation function to generate values between 2 points:
List<double> interpolate(double start, double end, int count) {
if (count < 2) {
throw Exception("interpolate: illegal count!");
}
final array = List.generate(count + 1, (index) => 0.0);
for (int i = 0; i <= count; ++i) {
array[i] = start + i * (end - start) / count;
}
return array;
}
Usage:
void main() {
final input = [1.0, 15.0];
print(interpolate(input.first, input.last, 4));
}
Result:
[1.0, 4.5, 8.0, 11.5, 15.0]
I want to find the sum of the digits of the number entered in Flutter. I want to encode this algorithm.
for example
x=1992
result=1+9+9+2=21
how can i do this with flutter
You can do in this way.
import 'dart:io';
void main() {
print('Enter X');
int X = int.parse(stdin.readLineSync()!);
int result = 0;
for (int i = X; i > 0; i = (i / 10).floor()) {
result += (i % 10);
}
print('Sum of digits\n$result');
}
Output
Enter X
123456
Sum of digits
21
transform the number into an String using String stringValue = x.toString();
create an array from each char using List<String> result = stringValue.split('');
sum each number transforming back using int.parse(result)
void main(){
int x = 1992;
String stringValue = x.toString();
List<String> result = stringValue.split('');
int sum = 0;
for(int i = 0 ; i < result.length; i++) {
int value = int.parse(result[i]);
sum = sum + value;
}
print(sum);
}
Result: 21
List<AudioWaveBar> bars = [];
var list = List<double>.generate(100, (i) => i as double)..shuffle();
for (var i = 0; i <= list.length; i++) {
bars.add(AudioWaveBar(
heightFactor: list[i],
color: widget.podcast.percentPlayed >= ((i + 1).toDouble() / list.length.toDouble())
? AppTheme.greenStart
: Colors.white10
)); }
I need to have a list of random doubles only (from 0 to 1), but random function doesn't add the numbers to a list and generate function only accepts int numbers that can't be casted. Any help? thanks!
The function Random().nextDouble() generates a random double between 0 and 1.
So just by specifying a max value u can get what u want, like so :
int maxValue = 1000;
var list = List<double>.generate(100, (i) => Random().nextDouble() * maxValue)..shuffle();
Hi i have been wondering if there is a way in which to convert binary numbers into decimal fractions.
I know how to change base as an example through this code
String binary = "11110010";
//I'd like to change this line so it produces a decimal value
String denary = int.parse(binary, radix: 2).toRadixString(10);
If anyone still wondering how to convert decimal to binary and the inverse:
print(55.toRadixString(2)); // Outputs 110111
print(int.parse("110111", radix: 2)); Outputs 55
int binaryToDecimal(int n)
{
int num = n;
int dec_value = 0;
// Initializing base value to 1, i.e 2^0
int base = 1;
int temp = num;
while (temp) {
int last_digit = temp % 10;
temp = temp / 10;
dec_value += last_digit * base;
base = base * 2;
}
return dec_value;
}
int main()
{
int num = 10101001;
cout << binaryToDecimal(num) << endl;
}
This is my c++ solution but you can implement any language
A project I am working on uses Apache Shiro as a security framework. Passwords are SHA1 hashed (no salt, no iterations). Login is SSL secured. However, the remaining part of the application is not SSL secured. In this context (no SSL) there should be a form where a user can change the password.
Since it wouldn't be a good idea to transmit it plainly it should be hashed on the client and then transmitted to the server. As the client is GWT (2.3) based, I am trying this library http://code.google.com/p/gwt-crypto, which uses code from bouncycastle.
However, in many cases (not all) the hashes generated by both frameworks differ in 1-4(?) characters.
For instance "happa3" is hashed to
"fe7f3cffd8a5f0512a5f1120f1369f48cd6f47c2"
by both implementations, whereas just "happa" is hashed to
"fb3c3a741b4e07a87d9cb68f3db020d6fbfed00a"
by the Shiro implementation and to
"fb3c3a741b4e07a87d9cb63f3db020d6fbfed00a"
by the gwt-crypto implementation (23rd character differs).
I wonder whether there is a "correct"/standard SHA1 hashing and whether there is a bug in one of the libraries or maybe my usage of them is flawed.
One of my first thoughts was related to different encodings or strange conversions due to different transport mechanisms (RPC vs. Post). To my knowledge though (and what puzzles me most), SHA1 hashes should differ completely with a high probability if there is just a difference of a single bit. So different encodings shouldn't be the issue here.
I am using this code on the client (GWT) for hashing:
String hashed = toHex(createSHA1Hash("password"));
...
private String createSHA1Hash(String passwordString){
SHA1Digest sha1 = new SHA1Digest();
byte[] bytes;
byte[] result = new byte[sha1.getDigestSize()];
try {
bytes = passwordString.getBytes();
sha1.update(bytes, 0, bytes.length);
int val = sha1.doFinal(result, 0);
} catch (UnsupportedEncodingException e) {}
return new String(result);
}
public String toHex(String arg) {
return new BigInteger(1, arg.getBytes()).toString(16);
}
And this on the server (Shiro):
String hashed = new Sha1Hash("password").toHex()
which afaics does something very similar behind the scenes (had a quick view on the source code).
Did I miss something obvious here?
EDIT: Seems like the GWT code does not run natively for some reason (i.e. just in development mode) and silently fails (it does compile, though). Have to find out why...
Edit(2): "int val = sha1.doFinal(result, 0);" is the line that makes trouble, i.e. if present, the whole code does not run natively (JS) but only in dev-mode (with wrong results)
You could test this version:
public class SHA1 {
public static native String calcSHA1(String s) /*-{
//
// A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined
// in FIPS 180-1
// Version 2.2 Copyright Paul Johnston 2000 - 2009.
// Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
// Distributed under the BSD License
// See http://pajhome.org.uk/crypt/md5 for details.
//
//
// Configurable variables. You may need to tweak these to be compatible with
// the server-side, but the defaults work in most cases.
//
var hexcase = 0; // hex output format. 0 - lowercase; 1 - uppercase
var b64pad = ""; // base-64 pad character. "=" for strict RFC compliance
//
// These are the functions you'll usually want to call
// They take string arguments and return either hex or base-64 encoded strings
//
function b64_sha1(s) { return rstr2b64(rstr_sha1(str2rstr_utf8(s))); }
function any_sha1(s, e) { return rstr2any(rstr_sha1(str2rstr_utf8(s)), e); }
function hex_hmac_sha1(k, d)
{ return rstr2hex(rstr_hmac_sha1(str2rstr_utf8(k), str2rstr_utf8(d))); }
function b64_hmac_sha1(k, d)
{ return rstr2b64(rstr_hmac_sha1(str2rstr_utf8(k), str2rstr_utf8(d))); }
function any_hmac_sha1(k, d, e)
{ return rstr2any(rstr_hmac_sha1(str2rstr_utf8(k), str2rstr_utf8(d)), e); }
//
// Perform a simple self-test to see if the VM is working
//
function sha1_vm_test()
{
return hex_sha1("abc").toLowerCase() == "a9993e364706816aba3e25717850c26c9cd0d89d";
}
//
// Calculate the SHA1 of a raw string
//
function rstr_sha1(s)
{
return binb2rstr(binb_sha1(rstr2binb(s), s.length * 8));
}
//
// Calculate the HMAC-SHA1 of a key and some data (raw strings)
//
function rstr_hmac_sha1(key, data)
{
var bkey = rstr2binb(key);
if(bkey.length > 16) bkey = binb_sha1(bkey, key.length * 8);
var ipad = Array(16), opad = Array(16);
for(var i = 0; i < 16; i++)
{
ipad[i] = bkey[i] ^ 0x36363636;
opad[i] = bkey[i] ^ 0x5C5C5C5C;
}
var hash = binb_sha1(ipad.concat(rstr2binb(data)), 512 + data.length * 8);
return binb2rstr(binb_sha1(opad.concat(hash), 512 + 160));
}
//
// Convert a raw string to a hex string
//
function rstr2hex(input)
{
try { hexcase } catch(e) { hexcase=0; }
var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
var output = "";
var x;
for(var i = 0; i < input.length; i++)
{
x = input.charCodeAt(i);
output += hex_tab.charAt((x >>> 4) & 0x0F)
+ hex_tab.charAt( x & 0x0F);
}
return output;
}
//
// Convert a raw string to a base-64 string
//
function rstr2b64(input)
{
try { b64pad } catch(e) { b64pad=''; }
var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var output = "";
var len = input.length;
for(var i = 0; i < len; i += 3)
{
var triplet = (input.charCodeAt(i) << 16)
| (i + 1 < len ? input.charCodeAt(i+1) << 8 : 0)
| (i + 2 < len ? input.charCodeAt(i+2) : 0);
for(var j = 0; j < 4; j++)
{
if(i * 8 + j * 6 > input.length * 8) output += b64pad;
else output += tab.charAt((triplet >>> 6*(3-j)) & 0x3F);
}
}
return output;
}
//
// Convert a raw string to an arbitrary string encoding
//
function rstr2any(input, encoding)
{
var divisor = encoding.length;
var remainders = Array();
var i, q, x, quotient;
// Convert to an array of 16-bit big-endian values, forming the dividend
var dividend = Array(Math.ceil(input.length / 2));
for(i = 0; i < dividend.length; i++)
{
dividend[i] = (input.charCodeAt(i * 2) << 8) | input.charCodeAt(i * 2 + 1);
}
//
// Repeatedly perform a long division. The binary array forms the dividend,
// the length of the encoding is the divisor. Once computed, the quotient
// forms the dividend for the next step. We stop when the dividend is zero.
// All remainders are stored for later use.
//
while(dividend.length > 0)
{
quotient = Array();
x = 0;
for(i = 0; i < dividend.length; i++)
{
x = (x << 16) + dividend[i];
q = Math.floor(x / divisor);
x -= q * divisor;
if(quotient.length > 0 || q > 0)
quotient[quotient.length] = q;
}
remainders[remainders.length] = x;
dividend = quotient;
}
// Convert the remainders to the output string
var output = "";
for(i = remainders.length - 1; i >= 0; i--)
output += encoding.charAt(remainders[i]);
// Append leading zero equivalents
var full_length = Math.ceil(input.length * 8 /
(Math.log(encoding.length) / Math.log(2)))
for(i = output.length; i < full_length; i++)
output = encoding[0] + output;
return output;
}
//
// Encode a string as utf-8.
// For efficiency, this assumes the input is valid utf-16.
//
function str2rstr_utf8(input)
{
var output = "";
var i = -1;
var x, y;
while(++i < input.length)
{
// Decode utf-16 surrogate pairs
x = input.charCodeAt(i);
y = i + 1 < input.length ? input.charCodeAt(i + 1) : 0;
if(0xD800 <= x && x <= 0xDBFF && 0xDC00 <= y && y <= 0xDFFF)
{
x = 0x10000 + ((x & 0x03FF) << 10) + (y & 0x03FF);
i++;
}
// Encode output as utf-8
if(x <= 0x7F)
output += String.fromCharCode(x);
else if(x <= 0x7FF)
output += String.fromCharCode(0xC0 | ((x >>> 6 ) & 0x1F),
0x80 | ( x & 0x3F));
else if(x <= 0xFFFF)
output += String.fromCharCode(0xE0 | ((x >>> 12) & 0x0F),
0x80 | ((x >>> 6 ) & 0x3F),
0x80 | ( x & 0x3F));
else if(x <= 0x1FFFFF)
output += String.fromCharCode(0xF0 | ((x >>> 18) & 0x07),
0x80 | ((x >>> 12) & 0x3F),
0x80 | ((x >>> 6 ) & 0x3F),
0x80 | ( x & 0x3F));
}
return output;
}
//
// Encode a string as utf-16
//
function str2rstr_utf16le(input)
{
var output = "";
for(var i = 0; i < input.length; i++)
output += String.fromCharCode( input.charCodeAt(i) & 0xFF,
(input.charCodeAt(i) >>> 8) & 0xFF);
return output;
}
function str2rstr_utf16be(input)
{
var output = "";
for(var i = 0; i < input.length; i++)
output += String.fromCharCode((input.charCodeAt(i) >>> 8) & 0xFF,
input.charCodeAt(i) & 0xFF);
return output;
}
//
// Convert a raw string to an array of big-endian words
// Characters >255 have their high-byte silently ignored.
//
function rstr2binb(input)
{
var output = Array(input.length >> 2);
for(var i = 0; i < output.length; i++)
output[i] = 0;
for(var i = 0; i < input.length * 8; i += 8)
output[i>>5] |= (input.charCodeAt(i / 8) & 0xFF) << (24 - i % 32);
return output;
}
//
// Convert an array of big-endian words to a string
//
function binb2rstr(input)
{
var output = "";
for(var i = 0; i < input.length * 32; i += 8)
output += String.fromCharCode((input[i>>5] >>> (24 - i % 32)) & 0xFF);
return output;
}
//
// Calculate the SHA-1 of an array of big-endian words, and a bit length
//
function binb_sha1(x, len)
{
// append padding
x[len >> 5] |= 0x80 << (24 - len % 32);
x[((len + 64 >> 9) << 4) + 15] = len;
var w = Array(80);
var a = 1732584193;
var b = -271733879;
var c = -1732584194;
var d = 271733878;
var e = -1009589776;
for(var i = 0; i < x.length; i += 16)
{
var olda = a;
var oldb = b;
var oldc = c;
var oldd = d;
var olde = e;
for(var j = 0; j < 80; j++)
{
if(j < 16) w[j] = x[i + j];
else w[j] = bit_rol(w[j-3] ^ w[j-8] ^ w[j-14] ^ w[j-16], 1);
var t = safe_add(safe_add(bit_rol(a, 5), sha1_ft(j, b, c, d)),
safe_add(safe_add(e, w[j]), sha1_kt(j)));
e = d;
d = c;
c = bit_rol(b, 30);
b = a;
a = t;
}
a = safe_add(a, olda);
b = safe_add(b, oldb);
c = safe_add(c, oldc);
d = safe_add(d, oldd);
e = safe_add(e, olde);
}
return Array(a, b, c, d, e);
}
//
// Perform the appropriate triplet combination function for the current
// iteration
//
function sha1_ft(t, b, c, d)
{
if(t < 20) return (b & c) | ((~b) & d);
if(t < 40) return b ^ c ^ d;
if(t < 60) return (b & c) | (b & d) | (c & d);
return b ^ c ^ d;
}
//
// Determine the appropriate additive constant for the current iteration
//
function sha1_kt(t)
{
return (t < 20) ? 1518500249 : (t < 40) ? 1859775393 :
(t < 60) ? -1894007588 : -899497514;
}
//
// Add integers, wrapping at 2^32. This uses 16-bit operations internally
// to work around bugs in some JS interpreters.
//
function safe_add(x, y)
{
var lsw = (x & 0xFFFF) + (y & 0xFFFF);
var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
return (msw << 16) | (lsw & 0xFFFF);
}
//
// Bitwise rotate a 32-bit number to the left.
//
function bit_rol(num, cnt)
{
return (num << cnt) | (num >>> (32 - cnt));
}
return rstr2hex(rstr_sha1(str2rstr_utf8(s)));
}-*/;
}
I'm using it in my client side sha generation and it worked well.