Very simple array, loop, and logical comparison issue

Question

Very simple question: I'm trying to compare values in an array and I'm completely stumped as to why my comparison logic is failing. Somehow, during the course of my loop, 6 is being evaluated as > 524. Any ideas as to what I'm doing wrong? I'm totally stumped. Here's the code, and thanks!

function highAndLow(numbers){

    var compArr = numbers.split(" ");

    var highNum = compArr[0]
    var lowNum = compArr[0];


      for (i = 1; i < compArr.length; i++) {
        if (compArr[i] > highNum) {
          highNum = compArr[i]
          console.log(highNum)
        }
      }

      for (i = 1; i < compArr.length; i++) {
        if (compArr[i] < lowNum) {
          lowNum = compArr[i]
        }
      }

      return highNum + " " + lowNum
}

highAndLow("4 5 29 54 4 0 -214 542 -64 1 -3 6 -6")

Again, I'm not sure how, but the result I'm getting in the console is 6 for the highNum (incorrect) and -214 for the lowNum (which is correct). Am I missing something obvious?

You're comparing strings, not numbers.

Barmar
– Barmar

2017-06-06 21:30:05 +00:00
Commented Jun 6, 2017 at 21:30 — Barmar
– Barmar, Commented Jun 6, 2017 at 21:30

Barmar · Accepted Answer · 2017-06-06 21:31:46Z

1

The elements of compArr are strings, so they're being compared lexicographically, not numerically. You should make an array of numbers:

var compArr = numbers.split(" ").map(Number);

function highAndLow(numbers){

    var compArr = numbers.split(" ").map(Number);

    var highNum = compArr[0]
    var lowNum = compArr[0];


      for (i = 1; i < compArr.length; i++) {
        if (compArr[i] > highNum) {
          highNum = compArr[i]
          console.log(highNum)
        }
      }

      for (i = 1; i < compArr.length; i++) {
        if (compArr[i] < lowNum) {
          lowNum = compArr[i]
        }
      }

      return highNum + " " + lowNum
}

console.log(highAndLow("4 5 29 54 4 0 -214 542 -64 1 -3 6 -6"));

answered Jun 6, 2017 at 21:31

Barmar

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Comments

yoursweater · Accepted Answer · 2017-06-06 21:36:31Z

edited to include Barmar's answer. Thanks Barmar!

I figured it out. My comparison was running to the edge of the array and trying to compare to undefined. Also, because of the way I had set things up, this method wouldn't work on strings with only two values. Here's my new code:

function highAndLow(numbers){

    var compArr = numbers.split(" ").map(Number);

    var highNum = compArr[0]
    var lowNum = compArr[0];

    if (compArr.length === 2) {
      if (compArr[1] > highNum) {
          highNum = compArr[1]
      }
      if (compArr[1] < lowNum) {
          lowNum = compArr[1]
      }

    } else {
        for (i = 1; i < compArr.length - 2; i++) {
          if (compArr[i] > highNum) {
            highNum = compArr[i]
          }
        }

        for (i = 1; i < compArr.length - 2; i++) {
          if (compArr[i] < lowNum) {
            lowNum = compArr[i]
          }
        }
      }

      return highNum + " " + lowNum

}

There's probably a better/cleaner way to do this, however.

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