Diagonals

#include <stdio.h>
#include <string.h>
#include <math.h>
#define SIZE 4

void pop_arr(int s,int a[SIZE][SIZE]);
void pr_arr(int s,int a[SIZE][SIZE]);
void main_diag(int s,int a[SIZE][SIZE]);//mirror main diagonal
void dop_diag(int s,int a[SIZE][SIZE]);//mirror additional diagonal

int main()
{
    int arr[SIZE][SIZE]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16};

    printf("\nORIGINAL ARRAY:\n");
    pr_arr(SIZE,arr);

    printf("\nAFTER MIRROWING MAIN DIAGONAL:\n");
    main_diag(SIZE,arr);
    pr_arr(SIZE,arr);

    printf("\nBACK TO ORIGINAL(THROUGHT MIRROWING MAIN):\n");
    main_diag(SIZE,arr);
    pr_arr(SIZE,arr);

    printf("\nAFTER MIRROWING ADD DIAGONAL:\n");
    dop_diag(SIZE,arr);
    pr_arr(SIZE,arr);

    printf("\nBACK TO ORIGINAL(THROUGHT MIRROWING ADD):\n");
    dop_diag(SIZE,arr);
    pr_arr(SIZE,arr);

    printf("\nCOMBINES MAIN AND ADD MIRROWING:\n");
    main_diag(SIZE,arr);
    dop_diag(SIZE,arr);
    pr_arr(SIZE,arr);

    printf("\nBACK TO ORIGINAL THROUGH MAIN AND ADD MIRROWING:\n");
    main_diag(SIZE,arr);
    dop_diag(SIZE,arr);
    pr_arr(SIZE,arr);

    return 0;
}
void pop_arr(int s,int a[SIZE][SIZE])
{
    int i,j;
    for(i=0;i<s;i++)
    {
        for(j=0;j<s;j++)
            a[i][j]= rand()%20-10;
    }
}

void pr_arr(int s,int a[SIZE][SIZE])
{
    int i,j;
    for(i=0;i<s;i++)
    {
        for(j=0;j<s;j++)
            printf("%d\t",a[i][j]);
        printf("\n");
    }
}
void main_diag(int s,int a[SIZE][SIZE])
{
    int i,j,temp;
    for(i=0;i<s;i++)
    {
        for(j=i;j<s;j++)
        {
           if(i!=j)
           {
               temp= a[i][j];
               a[i][j]= a[j][i];
               a[j][i]  = temp;
           }
        }
    }
}

void dop_diag(int s,int a[SIZE][SIZE])
{
    int i,j,temp,ti,tj;
    for(i=0;i<s;i++)
    {
        for(j=0;j<s-i;j++)
        {
            ti = s-j-1;
            tj = s-i-1;
           if(j!=s-i-1)//j!=s-i-1
           {
               temp= a[i][j];
               a[i][j]= a[ti][tj];
               a[ti][tj]  = temp;
           }
        }
    }
}