# freeCodeCamp Algorithm Challenge Guide: Repeat a string repeat a string

freeCodeCamp Algorithm Challenge Guide: Repeat a string repeat a string
0

#1

Remember to use `Read-Search-Ask` if you get stuck. Try to pair program and write your own code

### Problem Explanation:

The program is very simple, we have to take a variable and return that variable being repeated certain amount of times. No need to add space or anything, just keep repeating it into one single string.

## Hint: 1

You can’t edit strings, you will need to create a variable to store the new string.

try to solve the problem now

## Hint: 2

Create a loop to repeat the code as many times as needed.

try to solve the problem now

## Hint: 3

Make the variable created store the current value and append the word to it.

try to solve the problem now

Solution ahead!

## Basic Code Solution:

``````function repeatStringNumTimes(str, num) {
var accumulatedStr = '';

while (num > 0) {
accumulatedStr += str;
num--;
}

return accumulatedStr;
}
``````

### Code Explanation:

• Create an empty string variable to store the repeated word.
• Use a while loop or for loop to repeat code as many times as needed according to `num`
• Then we just have to add the string to the variable created on step one, and increase or decrease `num` depending on how you set the loop.
• At the end of the loop, return the variable for the repeated word.

## Intermediate Code Solution:

``````function repeatStringNumTimes(str, num) {
if(num < 0)
return "";
if(num === 1)
return str;
else
return str + repeatStringNumTimes(str, num - 1);
}
``````

### Code Explanation:

• This solution uses recursion.
• We check if `num` is negative and return an empty string if true.
• Then we check if it’s equal to 1 and in that case we return the string itself.
• If not, we add the string to a call of our function with `num` being decreased by 1, which will add another `str` and another… until eventually `num` is 1. And return that whole process.

## Advanced Code Solution:

``````function repeatStringNumTimes(str, num) {
return num > 0 ? str.repeat(num) : '';
}

repeatStringNumTimes("abc", 3);
``````

### Code Explanation:

• This solution takes a declarative approach.
• It is similar to the third solution, except it uses the ternary operator form of the `if` statement.

## NOTES FOR CONTRIBUTIONS:

• DO NOT add solutions that are similar to any existing solutions. If you think it is similar but better, then try to merge (or replace) the existing similar solution.
• Add an explanation of your solution.
• Categorize the solution in one of the following categories — Basic, Intermediate and Advanced.
• Please add your username only if you have added any relevant main contents. ( DO NOT remove any existing usernames)

See `Wiki Challenge Solution Template` for reference.

Repeat a string challenge - Tips please
Repeat a string repeat a string - part duex
#2

#3

#4

I used an array method, I would say it was a beginner way to do it.

function repeatStringNumTimes(str, num) {
var strArray=[];

for(i=0;i<num;i++){strArray.push(str);}
return strArray.join("");
}

#5

I used a bit different code and it worked fine:

function repeatStringNumTimes(str, num) {
// repeat after me
if (num > 0) {
return str.repeat(num);
} else {
return “”;
}
}

#6

function repeatStringNumTimes(str, num) {
// repeat after me
repeat = “” ;
for (;num > 0;repeat += str,num–){}
return repeat;

}

repeatStringNumTimes(“abc”, 3);

#7

i have solved this like below…

``````function repeatStringNumTimes(str, num) {
// repeat after me
var repeat="";
for (var i = 1; i<=num ; i++){
repeat = repeat.concat(str);
}
return repeat;

}

repeatStringNumTimes("myName", 4 );
``````

is there any problem in this way of approach for solving this problem

#8

Can someone explain why this didn’t work:

``````function repeatStringNumTimes(str, num) {
var re_peat = str.repeat(num);
if (num >= 0){
return re_peat;
} else {
return "";
}
}
``````

why can’t you store the method in a variable?
but this worked just fine:

``````function repeatStringNumTimes(str, num) {
//var re_peat = str.repeat(num);
if (num > 0){
return str.repeat(num);

} else {

return "";
}
}
``````

Thank you in advance.

#9

The advanced method here uses the repeat method…which is the best way but the challenge said not to for some reason…to make us work i guess.

i came up with.

``````function repeatStringNumTimes(str, num) {
return (num<1) ? "": str.concat(repeatStringNumTimes(str,num-1));}
``````

its just a spruced up version of the intermediate code. it uses concat instead of a plus sign and ternary operators. done this way its not much longer than using repeat.

#10

That’s my code:

``````function repeatStringNumTimes(str, num) {

var strRepeated = "";

for(var i=0; i<num; i++){
strRepeated +=  str;
}

return strRepeated;
}

//test
repeatStringNumTimes("*", 2);``````

#11

I noticed that a few people posted solutions that are VERY SIMILAR to the FCC solution, but using `for` loops with decalred `var i` rather than `while` loops incrementing `num` itself. @TatheerHussain @irakligeek

I ran some performance tests, and I found that using a `for` loop instead of a `while` loop takes almost TWICE as long! question is: why? is it because you are declaring a second variable in the `for` loop? is it that much faster just to use `num` instead of introducing `i` as well? or is there something about the difference between the two loops that I don’t understand?

1,000,000 repetitions of each function
with `for` loop and `var i`: 64.7 milliseconds
with `while` loop and incrementing `num`: 34.2 milliseconds

10,000,000 repetitions of each function
with `for` loop and `var i`: 562.6 milliseconds
with `while` loop and incrementing `num`: 313.6 milliseconds

100,000,000 repetitions of each function
with `for` loop and `var i`: 5.5 seconds
with `while` loop and incrementing `num`: 3.09 seconds

1,000,000,000 repetitions of each function
with `for` loop and `var i`: 54.8 seconds
with `while` loop and incrementing `num`: 30.7 seconds

#12

I solved this challenge with this:

function repeatStringNumTimes(str, num) {
// repeat after me
var more = ‘’;
for(var i = 0; i < num; i++){
if(num > 0){
more += str;
}else{
return ‘’;
}
}
return more;
}

repeatStringNumTimes(“abc”, 1);

#13

Basicly your top solution doesn’t work because the repeat function only allows values >= 0.
If num is negative it evaluates to an error : Uncaught RangeError: Invalid count value , and therefor JavaScript
wont progress.

So basicly the 2nd solution is the correct way, but you could have solved it that way too:

// store the function in re_peat with (str,num) parameters and return the result of str.repeat(num)
var re_peat = function (str, num) {
return str.repeat(num);
};

// still check if num > 0 to call the function with the Parameters, because see reason above.
if (num > 0)
{
return re_peat(str,num);
}
else
{
return “”;
}

Hope that helped.

#14

USING A FOR LOOP:
function repeatStringNumTimes(str, num) {
// repeat after me
var a="";
if (num>0)
{
for(i=1;i<=num; i++){
a += str;
}

}
return a;
}

repeatStringNumTimes("\$", 32);

#15

function repeatStringNumTimes(str, num) {
var texto ="";
if(num<0){
str = “”;
} else {
for(var i=0;i<num;i++){
texto+=str;
}
}
return texto;
}

repeatStringNumTimes(“abc”, 3);

#16
``````function repeatStringNumTimes(str, num) {

// repeat after me
if (num <= 0) return "";

return new Array(num+1).join(str);
}``````

#17

I solved it this way, but thanks to @jmbothe, I’ll switch to `while` loops going forward.

`function repeatStringNumTimes(str, num) { var newString = ''; // repeat after me for (i = 0;i < num; i++) { newString = newString + str; } return newString; } repeatStringNumTimes("abc", 3);`

#18

My solution ended up being an unoptimized version of advanced code solution using `repeat` method

``````function repeatStringNumTimes(str, num) {

//Positive num only
if (num <= 0){
return "";
}

return str.repeat(num);
}

repeatStringNumTimes("abc", 3);
``````

#19

This is how I solved it. The str.repeat pretty much solved the issues for me.

#20

The code I wrote seems to get the correct answer but the page wont recognise me passing. Any idea?

acc = “”;

function repeatStringNumTimes(str, num) {
if (num > 0) {
for (i = 0; i != num; i++) {
acc += str;
}
return acc;
}
return “”;
}

repeatStringNumTimes(“abc”, 3);