My code

=======

#include<iostream.h>

void identity(int a[4][4], int m){

int i=m, j=m;

for(i=0;i<4;i++){

for(j=0;j<4;j++){

if(i==j)

a[i][j]=1;

else

a[i][j]=0;

return a[i][j];

}

}

}

void main(){

int a[4][4];

int m=4;

identity(a[4][4], m);

cout<a[i][j]

}

cout<<'\n';

}

My problem

==========

Write a function 'identity' which returns a 1 if the array argument passed to it represents an identity matrix, and returns 0 otherwise. An identity matrix is an m by m array of integers, where the values of the elements on the principle diagonal (row subscript == col subscript)equal 1, and all other elements are 0. for

example:

1 0 0 0

0 1 0 0

0 0 1 0

0 0 0 1

is an identity matrix of order 4 by 4,

1 0 0

0 1 0

0 0 1

is an identity matrix of order 3 by 3,and

1 1 5

0 1 0

0 0 1

is NOT an identity matrix. The function identity is passed two arguments: the array, and the order of the matrix ( i e the size of the two dimensions). Thus the prototype of the function would be written as :int identity (int a[][], int m);where a is the array and m represents the number of rows and columns. You may assume that the number of rows always equals the number of columns for the array.

=======

#include<iostream.h>

void identity(int a[4][4], int m){

int i=m, j=m;

for(i=0;i<4;i++){

for(j=0;j<4;j++){

if(i==j)

a[i][j]=1;

else

a[i][j]=0;

return a[i][j];

}

}

}

void main(){

int a[4][4];

int m=4;

identity(a[4][4], m);

cout<a[i][j]

}

cout<<'\n';

}

My problem

==========

Write a function 'identity' which returns a 1 if the array argument passed to it represents an identity matrix, and returns 0 otherwise. An identity matrix is an m by m array of integers, where the values of the elements on the principle diagonal (row subscript == col subscript)equal 1, and all other elements are 0. for

example:

1 0 0 0

0 1 0 0

0 0 1 0

0 0 0 1

is an identity matrix of order 4 by 4,

1 0 0

0 1 0

0 0 1

is an identity matrix of order 3 by 3,and

1 1 5

0 1 0

0 0 1

is NOT an identity matrix. The function identity is passed two arguments: the array, and the order of the matrix ( i e the size of the two dimensions). Thus the prototype of the function would be written as :int identity (int a[][], int m);where a is the array and m represents the number of rows and columns. You may assume that the number of rows always equals the number of columns for the array.

Anyway, as posed in the question, one cannot write such as function (it ain't valid C or C++). If a was a flat array of m*m elements then that could be easily done.

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/* no point in passing int m=4 if a[4][4] is hard coded */

/* the question you were given is not possible to answer */

/* exactly as specified. but we cannot do much */

/* about that now... */

/* also the function should return an int not a void */

/* void identity(int a[4][4], int m) { */

int identity(int a[4][4], int m) {

/* no point initializing i and j as they are */

/* set in the loop */

/* int i=m; */

/* int j=m; */

int i;

/* you have hard-coded 4 in the for loops */

/* for(i=0;i<4;i++){ */

/* for(j=0;j<4;j++){ */

/* we should use 'm' instead */

for(i=0;i<m;i++){

/* declare j here where it is used */

/* this is nicer code */

int j;

for(j=0;j<m;j++){

/* this is CREATING an identity matrix */

/* NOT testing for one as was asked */

if(i==j)

a[i][j]=1;

else

a[i][j]=0;

/* this is not what should be returned */

return a[i][j];

}

}

/* no return value from here at all */

/* a good compiler will detect this error */

}

int main(int argc, char* argv[]) {

/* you haven't put any data into a[][] yet */

int a[4][4];

int m=4;

/* you haven't done anything with the */

/* return value from identity */

/* also the call is wrong .. you are passing */

/* the value of the [4][4] item of the array */

/* (which is outside it anyway) instead of the */

/* whole array */

/* identity(a[4][4], m); */

int result = identity(a, m);

/* i and j aren't defined */

/* and you should be printing the result of */

/* the call to identity(...); */

/* BTW: if this is supposed to be 'C' code */

/* then you cannot use 'cout<<' etc */

/* cout<<a[i][j]; */

cout << result;

cout<<'\n';

return 0;

}

/* I suggest you think about the question */

/* a bit more and come back to me */