This problem is very straight forward - you start with a string that represents a sentence in binary code, and you need to translate that into words. There is not a direct way to do this so you will have to translate twice.
You should first convert from binary to decimal before translating those values into characters.
Hint 2
Things are easier when focusing on smaller parts, divide the input to focus on one letter at a time.
Hint 3
Make sure that each time you transcode a character from binary to decimal, you reset whatever variable you used to keep track of the ones. Also do not forget to turn everything back into one string.
Solutions
Solution 1 (Click to Show/Hide)
function binaryAgent(str) {
var biString = str.split(" ");
var uniString = [];
/*using the radix (or base) parameter in parseInt, we can convert the binary
number to a decimal number while simultaneously converting to a char*/
for (var i = 0; i < biString.length; i++) {
uniString.push(String.fromCharCode(parseInt(biString[i], 2)));
}
// we then simply join the string
return uniString.join("");
}
// test here
binaryAgent(
"01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010 01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110 01110101 01101110 00100001 00111111"
);
Code Explanation
Separate the string into an array of strings separated by whitespace.
Create some variables that you will use along the way - the names are self explanatory for the most part.
Iterate through each binary string in the new array.
Convert to decimal by using parseInt(_binary_, 2). Use the second parameter to specify the base of the input numbers.
function binaryAgent(str) {
// Separate the binary code by space.
str = str.split(" ");
var power;
var decValue = 0;
var sentence = "";
// Check each binary number from the array.
for (var s = 0; s < str.length; s++) {
// Check each bit from binary number
for (var t = 0; t < str[s].length; t++) {
// This only takes into consideration the active ones.
if (str[s][t] == 1) {
// This is quivalent to 2 ** position
power = Math.pow(2, +str[s].length - t - 1);
decValue += power;
// Record the decimal value by adding the number to the previous one.
}
}
// After the binary number is converted to decimal, convert it to string and store
sentence += String.fromCharCode(decValue);
// Reset decimal value for next binary number.
decValue = 0;
}
return sentence;
}
// test here
binaryAgent(
"01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010 01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110 01110101 01101110 00100001 00111111"
);
Code Explanation
For each of these binary strings, check for the ones and ignore the zeroes.
For those that are one or active then convert them to decimal, this takes into account the position and the right power it needs to be raised to.
Store the power into the power variable by adding it to any previous ones on the variable decValue. This variable will add and add the powers of the active ones until the end of the loop and then return the decimal number.
Convert the final decimal outside of the inner loop and then convert it to ASCII and saving it to sentence along with any other text string already converted and stored.
Reset the variable decValue to avoid getting wrong decimals before continuing to the outer loop.
First we use split() to be able to work on each character as an Array element
Then use map() to process each element from binary to decimal using pareseInt()
Last we can use String.fromCharCode() to convert each ASCII number into the corresponding character
However fromCharCode() expects a series of numbers rather than an Array! We can use ES6 Spread Operator to pass in an Array of numbers as individual numbers. See here for more info; Spread Operator
Here is my version of the basic answer including explanatory comments:
function binaryAgent(str) {
var binaryArr=str.split(" "); //Splits the string into separate arrays, breaking at the white spaces
var uniString = [];//creates a uniString variable
for(var i=0;i<binaryArr.length;i++){ //for loop that runs through the binaryArr array
uniString.push //pushes the result of the following code into uniString
(String.fromCharCode //returns the created character Code numbers as strings e.g the first character code is 129 which makes the capital letter A
(parseInt(binaryArr[i], 2))); /*Analyses each element
of binaryArr and converts it from Binary Code into
Decimal character Codes by multiplying each element
from end to beginning by the power of 2 and adding
the results. E.g. the first array element of 01000001
= 129 because the last element is 2 to the power of
0 which is 1 multiplied by 1 so it remains 1. The
one before last is 2 to the power of 1 which is 2
but this is multiplied by 0 so it becomes 0. Most
of the numbers in this code are 0 so return 0 even though the power of 2 is increasing: 2pow2 = 4,
2pow3 = 8 etc. The only other element of this code
which is a 1 is the 7th from last which is 2pow7=128.
This means that we need to add 128+1 = 129.*/
}
return uniString.join(''); //Join all the elements of uniString with no white spaces between.
}
binaryAgent("01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010 01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110 01110101 01101110 00100001 00111111");
I am curious as to why key elements of these solutions (String.prototype.split and parseInt) are not mentioned either on the original challenge page or in the hints. I spent ages trying to work out how to do this without ever finding a reference to either of these two methods. Admittedly .split has come up before and I should have considered using it myself but parseInt has not come up before. I feel that I am force to “cheat” by looking at the answers because I am given insufficient information to work it out by myself.
Why wasn’t parseInt() included? As far as I can tell the curriculum hadn’t introduced parseInt up to this point and its use is necessary to complete this challenge. I had to Google convert binary to decimal which felt like cheating
function binaryAgent(str) {
var arr = str.split(" "),newArr=[];
for(var a in arr){
newArr.push(String.fromCharCode(parseInt(arr[a],2)));
}
return newArr.join("");
}
Because I was trying to pass this algorithm with information that we’d learned (and we hadn’t learned about parseInt), here’s my solution using a recursion to parse a binary element.
function binaryAgent(str) {
return str.split(' ').map(function(bin) { return String.fromCharCode(parseBinary(bin));}).join('');
}
function parseBinary(str)
{
if (str.length === 0)
return 0;
return str[0] * (2 ** (str.length - 1)) + parseBinary(str.slice(1));
}
First of all, the think way is important, so just divide a big problem into step by step way to solve.
function binaryAgent(str) {
// Step1: split this string into some single word
// Step2: change the 01 to number
// Step3: use fromCharCode(num) to get the single word
// Step3: Combine these single word
// In action, this line secStr.push(String.fromCharCode((parseInt(newStr[i], 2))));
// I have think of parseInt(newStr[i], 2), but above that part, I don't know good.
// In general, my think way is right, that is good for me
var newStr = str.split(' ');
var secStr = [];
for (i=0;i < newStr.length; i++) {
secStr.push(String.fromCharCode((parseInt(newStr[i], 2))));
}
return secStr.join('');
// return str.charCodeAt();
}
binaryAgent("01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010
01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110
01110101 01101110 00100001 00111111");
i just make an array using split then map each element first turning it to ascii code then calling the string constructor fromCharCode on that ascii code
all thats left is to use join and then we have our english
if you didn’t already know parseInt takes a second argument of radix - which i only recently learned about…2 is binary
