Fill a nxn matrix in spiral order from 1 to n² - c

Question

I was supposed to fill an nxn matrix in spiral order from 1 to n² using functions and then print its result but I don't know why my code doesn't function can anyone help please?
The principle was to create different functions, each filling the matrix at different time intervals then calling those functions in the main program which prints them in a spiral matrix.
#include <stdio.h>
#include <stdlib.h>
/* initializing the array and variables for the whole program*/
int A[5][5],top,bottom,left,right;
int FillRowForward(int A[5][5],int top,int left,int right,int z)
/*function that fills the top of the matrix from left to right*/
{ left = 0;
for(top=left,right=0;right<=4;right++)
{
A[top][right]=z;
z++;
}
return A[top][right];
}
int FillRowBackwards(int A[5][5],int bottom,int left,int right,int z)
/*fills the lower part from right to left*/
{ bottom =4;
for(left=bottom,right=4;right>=0;right--)
{
A[left][right-1]=A[left][right]+z;
}
return A[left][right-1];
}
int FillColumnDownward(int A[5][5],int top,int bottom,int left,int z)
/*fills the last column from top to bottom*/
{
left=0;
for(top=left,bottom=4;top<=4;top++)
{
A[top+1][bottom]= A[top][bottom]+z;
}
return A[top][bottom];
}
int FillColumnUpward(int A[5][5],int top,int bottom,int left, int z)
/*fills the first column from bottop to top*/
{
left =0;
for(bottom=left,top=0;bottom>=1;bottom--)
{
A[bottom-1][top]=A[bottom][top]+z
}
return A[bottom][top];
}
int main()
{
int i,j,k=1;
while(k<5*5){
int FillRowForward(int A[5][5],int top,int left,int right,int k);
top++;
int FillColumnDownward(int A[5][5],int top,int bottom,int right,int k);
right--;
int FillRowBackwards(int A[5][5],int bottom,int left,int right,int k);
bottom--;
int FillColumnUpward(int A[5][5],int top,int bottom,int left,int k);
}
//prints the matrix
for(i=0;i<=4;i++)
for(j=0;j<=4;j++)
printf("%d",A[i][j]);
return 0;
}

Answer 1

You have a number of problems like:
int FillRowForward(int A[5][5],int top,int left,int right,int k);
not being a function call and that you you never change k, i.e. you have an endless loop.
This solution uses a variable direction to track the current direction of filling the matrix.
#include <stdio.h>
#define ARRSIZE 10
int main()
{
int A[ARRSIZE][ARRSIZE] = { 0 };
int i=0, j=0;
int direction = 0;
for(int k = 1; k <= (ARRSIZE*ARRSIZE); ++k)
{
A[i][j] = k;
switch (direction)
{
case 0 : // Go rigth
if (((j + 1) == ARRSIZE) || (A[i][j+1] != 0))
{
// Switch direction
direction = 1;
++i;
}
else
{
++j;
}
break;
case 1 : // Go down
if (((i + 1) == ARRSIZE) || (A[i+1][j] != 0))
{
// Switch direction
direction = 2;
--j;
}
else
{
++i;
}
break;
case 2 : // Go left
if (((j - 1) == -1) || (A[i][j-1] != 0))
{
// Switch direction
direction = 3;
--i;
}
else
{
--j;
}
break;
case 3 : // Go up
if (((i - 1) == -1) || (A[i-1][j] != 0))
{
// Switch direction
direction = 0;
++j;
}
else
{
--i;
}
break;
}
}
for(i=0; i<ARRSIZE; i++)
{
for(j=0; j<ARRSIZE; j++)
printf("%4d",A[i][j]);
printf("\n");
}
return 0;
}
Output:
1 2 3 4 5 6 7 8 9 10
36 37 38 39 40 41 42 43 44 11
35 64 65 66 67 68 69 70 45 12
34 63 84 85 86 87 88 71 46 13
33 62 83 96 97 98 89 72 47 14
32 61 82 95 100 99 90 73 48 15
31 60 81 94 93 92 91 74 49 16
30 59 80 79 78 77 76 75 50 17
29 58 57 56 55 54 53 52 51 18
28 27 26 25 24 23 22 21 20 19

Answer 2

You have a couple of problems here:
I suppose there is no need for global variables, so you can define everything in the main() function
As already pointed out "In main() you are only providing declarations of the functions, not calling them. "
You have an infinite loop in main() function because you never increased var k
Try to avoid using numbers in your function, use variables or symbolic constants instead. No difference on such small projects, but in bigger projects, you can easily confuse them, also if you want to change, you must change every value, etc.
Your functions are not doing what they are supposed to do. You can write something like this (I found my old program and modified it a bit):
#include <stdio.h>
void print_mat(int mat[][5], int m, int n)
{
int i,j;
for(i = 0; i < m; i++)
{
for(j = 0; j < n; j++)
{
printf("%d\t", mat[i][j]);
}
printf("\n\n");
}
printf("\n");
}
void spiral(int mat[][5], int m, int n)
{
int i, k = 0, l = 0;
int counter = 1;
while(k < m && l < n)
{
for(i = l; i < n; i++)
{
mat[k][i] = counter++;
}
k++;
for(i = k; i < m; i++)
{
mat[i][n-1] = counter++;
}
n--;
if(k < m)
{
for(i = n-1; i >= l; i--)
{
mat[m-1][i] = counter++;
}
m--;
}
if(l < n)
{
for(i = m-1; i >= k; i--)
{
mat[i][l] = counter++;
}
l++;
}
}
}
int main()
{
int mat[5][5];
int n = 5;
spiral(mat,n,n);
print_mat(mat,n,n);
return 0;
}
Since you need to create different functions, you can try to divide this spiral() function into several smaller functions, it can be a good exercise.