CODEWITHSUNDEEP
javascriptarrays
Scott
Scott

Reputation: 25

TypeError on a Seemingly Simple Loop Through an Array

I'm trying to create a very simple nested for loop to print out every item in an NxN (for any N) array. It seems easy, but I keep getting this error:

"TypeError: Cannot read property '0' of undefined"

I've tried multiple ways of accessing each item/sub-item in the array, but no luck. I keep getting the same error. (And the array bing fed into the function is definitely NxN.)

This is my code:

const twoDimensionalArray = [
    [3, 4, 2, 4],
    [2, 1, 5, 7],
    [5, 3, 3, 2],
    [3, 6, 1, 5]
];

function printMatrix(arr) {
    for (let i = 0; i < arr.length; i++) {
        for (let j = 0; j < arr.length[i]; i++) {
            console.log(arr[i][j]);
        };
    };
}

console.log(printMatrix(twoDimensionalArray));

Upvotes: 1

Views: 45

Answers (4)

Dadsquatch
Dadsquatch

Reputation: 566

import React, { Component, Fragment } from "react";

class App extends Component {
  constructor() {
    super();
    this.state = {
      twoDimensionalArray: [
        [3, 4, 2, 4],
        [2, 1, 5, 7],
        [5, 3, 3, 2],
        [3, 6, 1, 5]
      ]
    };
    this.printMatrix(this.state.twoDimensionalArray);
  }

  printMatrix = arr => {
    arr.forEach(sub => {
      sub.forEach(item => {
        console.log(item);
      });
    });
  };

  render() {
    return <Fragment />;
  }
}

export default App;

Upvotes: 0

maazadeeb
maazadeeb

Reputation: 6112

You could use for..of to stop worrying about the indices. It becomes really simple.

const twoDimensionalArray = [
  [3, 4, 2, 4],
  [2, 1, 5, 7],
  [5, 3, 3, 2],
  [3, 6, 1, 5]
];

function printMatrix(arr) {
  for (let i of arr) {
    for (let j of i) {
      console.log(j);
    }
  }
}

printMatrix(twoDimensionalArray);

This has been mentioned in a comment above, as well.

Upvotes: 1

saravana manikandan
saravana manikandan

Reputation: 191

Please use below code with small correction. always try to store the intermediate stage into local variables and use it for better performance

function printMatrix(arr) {
    let mainArrayLength = arr.length;
    for (let i = 0; i < mainArrayLength; i++) {
        let subArray = arr[i];
        let subArrayLength = subArray.length;
        for (let j = 0; j < subArrayLength ; i++) {
            console.log(subArray[j]);
        };
    };
}

Upvotes: 1

ic3b3rg
ic3b3rg

Reputation: 14927

Here's your code with the corrections pointed out in the comments

  1. arr.length[i] -> arr[i].length
  2. second i++ -> j++
  3. console.log(printMatrix(twoDimensionalArray)) -> printMatrix(twoDimensionalArray)

const twoDimensionalArray = [
    [3, 4, 2, 4],
    [2, 1, 5, 7],
    [5, 3, 3, 2],
    [3, 6, 1, 5]
];

function printMatrix(arr) {
    for (let i = 0; i < arr.length; i++) {
        for (let j = 0; j < arr[i].length; j++) {
            console.log(arr[i][j]);
        };
    };
}

printMatrix(twoDimensionalArray);

Upvotes: 2

Related Questions