2 simple array errors?

Question

I created a method that needs to check the range of a multidimensional array and make sure each value in the 2D array is smaller than or equal to the length of the array.

public static boolean method(int[][] solution){
        //check rows for 1-N
        for (int i=0; i < solution.length; i++){
                if (solution[i] > solution.length)
                return false; //check rows
            }

        //check columns for 1 - N
        for (int j = 0; j<solution.length; j++){
            //get a column in the one dimensional array
            int[] column = new int[solution.length];
            for (int i=0; i < solution.length; i++){
                column[i] = solution[i][j];
            }
            if (column[i] > solution.length)
                return false; //check columns

        }
    return true;
    }

However, the errors I receive are follows:

Program.java:99: error: bad operand types for binary operator '>'
                                if (solution[i] > solution.length)
                                                ^
  first type:  int[]
  second type: int
Program.java:110: error: cannot find symbol
                        if (column[i] > solution.length)
                                   ^
  symbol:   variable i
  location: class Program
2 errors

Perhaps for the first error i need to get the array value instead of comparing the array? Not sure..

Rahul · Accepted Answer · 2013-11-14 04:08:00Z

4

First, you can't compare an array with an int value

if (solution[i] > solution.length) // solution is a 2-d array and thus solution[i] is a 1-d array
// which can't be compared with an int value

and second, the i was declared in the for loop, and thus it's not visible outside its scope.

for (int i=0; i < solution.length; i++){
    column[i] = solution[i][j];
} // scope of i is over here
if (column[i] > solution.length) // that's why you can't access `i` here
    return false;

You either need to use j or declare the i before the for, so that you can use it after it or probably, move the if inside the inner for loop(and that seems to be the right way for your problem as well).

edited Nov 14, 2013 at 4:08

answered Nov 14, 2013 at 3:53

Rahul

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5 Comments

user2913669 Over a year ago

i thought solution[i] is comparing the value inside the array to the int?

user2913669 Over a year ago

oh what a dumb mistake on the second error. sorry its been a long night

user2913669 Over a year ago

so how can i compare the value INSIDE the array to the interger value solution.length?

Rahul Over a year ago

I'm really not sure what the first for loop does. Can you tell what exactly you want to do, so that I can suggest accordingly?!

Rahul Over a year ago

I feel that the first for is not at all required, as you don't need to compare rows separately as such. With 2 nested for loops, you can iterate over all the rows & columns of the 2-d array and do the comparison.

Christian Tapia · Accepted Answer · 2013-11-14 03:54:47Z

1

You are using i outside the for loop, maybe you want to use j instead.

answered Nov 14, 2013 at 3:54

Christian Tapia

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Comments

Isuru Gunawardana · Accepted Answer · 2013-11-14 03:56:09Z

0

Its because, solution is a 2d array.

int[][] solution;

and to get this work it should be,

if(solution[][] > solution.length)

answered Nov 14, 2013 at 3:56

Isuru Gunawardana

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Pratik Shelar · Accepted Answer · 2013-11-14 03:58:58Z

0

I suppose this much code should suffice

public static boolean method(int[][] solution) {
    // check rows for 1-N
    for (int i = 0; i < solution.length; i++) {
        for (int j = 0; j < solution[i].length; i++) {
            if (solution[i][j] > solution.length)
                return false; // check rows
        }
    }

    return true;
}

answered Nov 14, 2013 at 3:58

Pratik Shelar

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1 Comment

user2913669 Over a year ago

that's correct. but i was trying to follow something in my book.

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