let cows = 4;
let width = 4;
let string = cows.toString();
while(string.length < width) {
string = "0" + string;
}
console.log(string);
This code will be printed as 0004..what i dont understand is why it doesnt print out 04040404?
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1Why not put a console log inside the while loop and see?evolutionxbox– evolutionxbox2021-03-31 09:16:30 +00:00Commented Mar 31, 2021 at 9:16
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Why do you expect that output? The code is only ever prepending a zero to the current string?evolutionxbox– evolutionxbox2021-03-31 09:25:06 +00:00Commented Mar 31, 2021 at 9:25
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1 Answer
So, at the start, your string is "4".
Then you enter the while loop, and your string becomes "04".
The condition isn't met yet, so you loop and add another '0' to the beginning of your string, becoming "004".
You loop one more time, adding again '0' to the start of the string, making it "0004".
Here your condition is met, and you exit the loop.
To obtain the result you had in mind, something like this would've worked
let cows = 4;
let width = 8;
let string = cows.toString();
string = "0" + string;
while(string.length < width) {
string +=string;
}
console.log(string);
5 Comments
CherryDT
In case of a width that's a factor of two, yes, otherwise this won't give the desired result.
serde
thank you for the response but why does the while loop adds the 0 in the beginning of the string and not the end?
Julien Ripet
@Valch Because the order matters. if you write
string + 0 , you'll have "40", but if you write 0 + string, you get "04"serde
alright, sorry if im being stupid, why is the while loop ignoring the string value but adds only the 0 even tho its "0" + string?
Julien Ripet
@valch No worries, we all started somewhere. The string value is not being ignored, otherwise you would just write over whatever is inside the variable
string, and you would end up with "0" at the console.log. Picture a box, in which you place a paper with "4" written on it. Then you take out the paper, staple another paper with "0", and place the result back in the box. And again, and again. That's what is happening