IF THEN ELSE with Negative Numbers - Basic Java

JavaScript
1

Tell us what’s happening:
Describe your issue in detail here.

Hello everyone. I have gone to the “hint” area and see that I nuked the ever living crap out of this. But I see how there is an easy way in the hints - but would someone PLEASE explain to me why this is giving me the console:

“Starting with highest number: -72
Looking at the next NEGATIVE number: -3
The current highest number is: -72
If -3 is < -72
Is -3 > ‘-72’?
NOPE!
-3 is NOT > ‘-72’
The highest number is still -72”

I do NOT get why it thinks that -3 is not larger than -72.

Please help. Thank you all.

  **Your code so far**


function largestOfFour(arr) {
let num = [];

for (let i = 0; i < arr.length; i++){
  console.log("-----------------------")
  console.log("Round # "+i);
   num.push([0]);
   
    for (let k = 0; k < arr[i].length; k++) {
      console.log("----------")
      console.log("Starting with highest number: " + num[i]);

  // IF IT'S A NEGATIVE NUMBER   

          if (Math.sign(arr[i][k]) === -1)
          {
            console.log("Looking at the next NEGATIVE number: " + arr[i][k]);
            console.log("The current highest number is: "+num[i]);
            console.log("If " + arr[i][k] + " is < " + num[i])
            if (arr[i][k] < num[i]) {
              console.log("Is " + arr[i][k] + " < "+ + num[i]) 
              num[i]=arr[i][k];
              console.log("It is! (Negative)")
              console.log("Highest number is now "+ num[i]) 
                
                  } else 
                  {
                    console.log("Is " + arr[i][k] + " > "+ "'" + num[i]+"'?") 
                    console.log("NOPE!");
                    console.log(arr[i][k] + " is NOT > "+ "'" + num[i]+"'")
                    console.log("The highest number is still "+num[i]); 
                      }
        
          } 
          //IF it's a POSITIVE NUMBER
          else if (Math.sign(arr[i][k]) === 1)
              {
              console.log("Looking at the next POSITIVE number: " + arr[i][k]);
                if(arr[i][k] > num[i]) 
                {
                  console.log("Is " + arr[i][k] + " > " + num[i]+"?") 
                  num[i]=arr[i][k];
                  console.log("It is!")
                  console.log("Highest number is now "+ "'" + num[i]+"'") 
                } else 
                      {
                    console.log("Is " + arr[i][k] + " > "+ "'" + num[i]+"'?") 
                    console.log("NOPE!");
                    console.log(arr[i][k] + " is NOT > "+ "'" + num[i]+"'")
                    console.log("The highest number is still "+num[i]); 
                      }

              }

}
console.log("The Largest numbers so far are: " + num);
}




console.log(num);
return num;
}

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [-72, -3, -17, -10]]);

  **Your browser information:**

User Agent is: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36

Challenge: Return Largest Numbers in Arrays

Link to the challenge:

2

You seem to be turning yourself about with this positive/negative divide. You shouldn’t do anything different for positive or negative numbers.

I suspect what sent you down this path is this:

Starting with highest number: 0

0 is a bad ‘guess’ for the maximum. You should instead ‘guess’ is one of the values you know is in the sub-array.

I got your code to work by cutting out the ‘NEGATIVE’ logic and changing one other line:

   num.push([0]);

There are two bugs with this line.

Side note though, all this console.log stuff is great! Exactly the sort of thing I do when debugging.

3

Jeremy,

So you just completely removed the whole section under my negative number check?

4

And thank you! I felt super “overboard” posting it here, but I was going crazy!

5

Well, that and tidied up braces so that only the positive logic was retained. Then I changed the initial ‘guess’ for what the highest number is. You can’t use 0 for this to work out right.

By the way, you can get a bit more readable output when logging the array by using:

console.log("The highest number is still " + num[i]);
6

Jeremy,

I deleted the negative section and start out the “guess” as you put it with:

let k=0
num.push(arr[0][k]);

now I get in the console for when there is a negative num

Round # 3
----------
Starting with highest number: 4
----------
Starting with highest number: 4
----------
Starting with highest number: 4
----------
Starting with highest number: 4
What am I messing up/not getting?
7

arr[0][k] won’t work, but it is close. All of the entries in sub-array 3 are smaller than the first entry in sub-array 0.

8

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