Having problem with Array practice excises

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 (ie 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.