Convert the following methods from Java to C and then write a function to test each output with at least 4 test cases to see if the method work correctly.

Question

//Convert an 2D array to a string

    String int2DArrayToString(int[][] input)

    {

        return Arrays.stream(input).map(x -> Arrays.stream(x).

                mapToObj(i -> String.format(" % 6d", i))

                .reduce("", (a,b) -> a + b)).reduce("", (a,b) -> a + b+'\n');

    }

    //Matrix Addition

int[][] mAdd (int[][]a, int[][] b)

    {

        if((a.length != b.length) && (a[0].length != b[0].length) ) return null;

        return IntStream.range(0, a.length).mapToObj(v 

                -> IntStream.range(0, a[0].length).map(e 

                        -> a[v][e] + b[v][e]).toArray()).toArray(int[][]::new);

    }

    // Identity matrix

    int[][] iN (int n)

    {

        

        return IntStream.range(0, n).mapToObj(v

                -> IntStream.range(0, n).map(e 

                        -> (e!=v)? 0:1

                ).toArray()

            ).toArray(int[][]::new);

    }

    // Find the Average of a 2D array

   double average (int [][]input)

    {

        return IntStream.range(0, input.length).mapToDouble(v ->

                IntStream.range(0, input[v].length).mapToDouble(e 

                        -> input[v][e]

                ).reduce(0.0, (a,b) ->a+b)/input[v].length

            ).reduce(0, (a,b) ->a+b)/input.length;

    }

int[] question2(int[] input)

    {

        return IntStream.range(0, input.length).map(i 

                -> IntStream.range(i, input.length).map(e 

                        -> input[i]

                ).reduce(0, (a,b)->a+b)

            ).toArray();

    }

If a test pass, then you need to state that it has passed in a green color, however if it fails then you need to display that it has failed in a red color.

Answer 1

You are not going to be able to translate them EXACTLY because the java array has the length property while C does not. You must pass the dimensions of the array matrix in C. Moreover, the matrices do not have to be square. You can add , for example, TWO 5x3 arrays.

The same is true for the average() method

Next, in Java, the methods RETURN the result as an array, which is C is a memory leak.

The CALLER shall be responsible for freeing the matrix or string that is returned by these

functions which is a BAD idea and a BAD practice.

My recommendation is to change the interface and pass the following data structure:

#define MAX_MATRIX_BUFF_SIZE (2048)

// matrix data structure

typedef struct _TMatrix

{

int ** matrix;

int nRows;

int nColumns;

} * TMatrix;

void int2DArray (TMatrix, char * matrixBuff);

int mAdd(TMatrix A, TMatrix B, TMatrix sumResult);

int iN (TMatrix identityMatrix, int n);

double average (TMatrix matrix);

Finally, It is very unclear what is being done in the question2 method. Why are you doing a double mapping?

Please give examples of input and how the output array is created from these mappings.

I honestly and humbly admit I am very confused as to what is going on with that particular method.

Fortunately, I was able to get your code into a compile-able state and verify that the matrix methods

deliver as promised. Code below. However, I had to research the packages to import.

Clarify these changes are acceptable and send an email. I will then generate the C code for you.

-----------------------------------------

//Your code

import java.util.*;

import java.util.Arrays;

import java.util.stream.*;

class Jeff

{

String int2DArrayToString(int[][] input)

{

return Arrays.stream(input).map(x -> Arrays.stream(x).

mapToObj(i -> String.format(" % 6d", i))

.reduce("", (a,b) -> a + b)).reduce("", (a,b) -> a + b+'\n');

}

//Matrix Addition

int[][] mAdd (int[][]a, int[][] b)

{

if((a.length != b.length) && (a[0].length != b[0].length) ) return null;

return IntStream.range(0, a.length).mapToObj(v

-> IntStream.range(0, a[0].length).map(e

-> a[v][e] + b[v][e]).toArray()).toArray(int[][]::new);

}

// Identity matrix

int[][] iN (int n)

{

return IntStream.range(0, n).mapToObj(v

-> IntStream.range(0, n).map(e

-> (e!=v)? 0:1

).toArray()

).toArray(int[][]::new);

}

// Find the Average of a 2D array

double average (int [][]input)

{

return IntStream.range(0, input.length).mapToDouble(v ->

IntStream.range(0, input[v].length).mapToDouble(e

-> input[v][e]

).reduce(0.0, (a,b) ->a+b)/input[v].length

).reduce(0, (a,b) ->a+b)/input.length;

}

int[] question2(int[] input)

{

return IntStream.range(0, input.length).map(i

-> IntStream.range(i, input.length).map(e

-> input[i]

).reduce(0, (a,b)->a+b)

).toArray();

}

public static void main(String args[])

{

Jeff x = new Jeff();

int n=4;

int A[][] = new int[n][n];

int B[][] = new int[n][n];

for (int rowLoop=0; rowLoop<n; rowLoop++)

{

for (int columnLoop=0; columnLoop<n; columnLoop++)

{

A[rowLoop][columnLoop] = 2*(rowLoop+columnLoop)+1; //odds

B[rowLoop][columnLoop] = 2*(rowLoop+columnLoop)+2; //evens

}

}

/* -----------------------------------

cells contain {total,A-entry,B-entry}

columnLoop

rowLoop 0 1 2 3

----------------------------------------------------------

0 {0,1,2} {1,3,4} {2,5,6} {3,7,8}

1 {1,3,4} {2,5,6} {3,7,8} {4,9,10}

2 {2,5,6} {3,7,8} {4,9,10} {5,11,12}

3 {3,7,8} {4,9,10} {5,11,12} {6,13,14}

------------------------------ */

String strA = x.int2DArrayToString(A);

String strB = x.int2DArrayToString(B);

System.out.println(">"+strA+"<");

System.out.println(">"+strB+"<");

int [][] C = x.mAdd(A,B);

String strC = x.int2DArrayToString(C);

System.out.println(strC);

int [][] I4 = x.iN(4);

String strI4 = x.int2DArrayToString(I4);

System.out.println(strI4);

double mAvg = x.average(C);

System.out.println(mAvg);

int [] v = {6,9,4};

int V[] = x.question2(v);

for (int iLoop=0; iLoop<V.length; iLoop++) { System.out.print(V[iLoop]+" "); }

}

}