C programming / what is the difference between these two codes [closed] - c

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What is the difference between these two codes? I think it's same code.
It can't operate both of codeup and Visual Studio.
codeup.kr 1505 problem
The problem for array
when you put number it
it makes num*num array
For example, given num = 3, it creates:
1 2 3
8 9 4
7 6 5
Code 1:
#include<stdio.h>
#include<string.h>
int main()
{
int tile[52][52];
int x, y;
int num;
int start = 1;
int check = 1, complete = 1;
int i;
scanf("%d", &num);
memset(tile, 0, 4 * 52 * 52);
tile[0][1] = 10;
tile[1][num + 1] = 10;
tile[num + 1][num + 1] = 10;
tile[num + 1][0] = 10;
x = 1; y = 1;
for (i = 0; i <= 3000; i++)
{
switch (check)
{
case 1:
{
if (tile[x][y + 1] != 0)
{
check += 1;
break;
}
tile[x][y++] = start;
start++;
complete++;
break;
}
case 2:
{
if (tile[x + 1][y] != 0)
{
check += 1;
break;
}
tile[x++][y] = start;
start++;
complete++;
break;
}
case 3:
{
if (tile[x][y - 1] != 0)
{
check += 1;
break;
}
tile[x][y--] = start;
start++;
complete++;
break;
}
case 4:
{
if (tile[x - 1][y] != 0)
{
check = 1;
break;
}
tile[x--][y] = start;
start++;
complete++;
break;
}
}
if (complete == num*num)
{
break;
}
}
if (num % 2 == 0)
{
tile[x][y] = start;
}
else
{
tile[x][y++] = start;
}
for (x = 1;x <= num; x++)
{
for (y = 1; y <= num; y++)
{
printf("%d ", tile[x][y]);
}
printf("\n");
}
}
This code operates in Visual Studio.
#include<stdio.h>
int main()
{
int tile[52][52];
int x, y;
int num;
int start = 1;
int check = 1, complete = 1;
int i;
scanf("%d", &num);
for (x = 0;x <= num; x++)
{
for (y = 0; y <= num; y++)
{
tile[x][y] = 0;
}
}
tile[0][1] = 10;
tile[1][num+1] = 10;
tile[num + 1][num + 1] = 10;
tile[num + 1][0] = 10;
x = 1; y = 1;
for (i = 0; i <= 3000; i++)
{
switch (check)
{
case 1:
{
if (tile[x][y + 1] != 0)
{
check += 1;
break;
}
tile[x][y++] = start;
start++;
complete++;
break;
}
case 2:
{
if (tile[x + 1][y] != 0)
{
check += 1;
break;
}
tile[x++][y] = start;
start++;
complete++;
break;
}
case 3:
{
if (tile[x][y - 1] != 0)
{
check += 1;
break;
}
tile[x][y--] = start;
start++;
complete++;
break;
}
case 4:
{
if (tile[x - 1][y] != 0)
{
check = 1;
break;
}
tile[x--][y] = start;
start++;
complete++;
break;
}
}
if (complete == num*num)
{
break;
}
}
if (num % 2 == 0)
{
tile[x][y] = start;
}
else
{
tile[x][y++] = start;
}
for (x = 1;x <= num; x++)
{
for (y = 1; y <= num; y++)
{
printf("%d ", tile[x][y]);
}
printf("\n");
}
}

Answer 1

The difference:
$ diff -w one.c two.c2,3d1
< #include<string.h>
<
14,15c12,16
< memset(tile, 0, 4 * 52 * 52);
<
---
> for (x = 0; x <= num; x++) {
> for (y = 0; y <= num; y++) {
> tile[x][y] = 0;
> }
> }
95a97
>
so, the first one uses memset to set all entries of tile to 0 (zero) and the second one uses a loop to set only the entries of tile to zero that are used, the content of the rest of the cells is undefined, could be everything. You can look for some places where x and/or y are outside of 0 <= x <= num < 52 in your code, or step through with a debugger, or use printf()s to find the exact places.
If you do not want to use memset() or are not able too: just change the loop to zero every cell out:
for (x = 0; x < 52; x++) {
for (y = 0; y < 52; y++) {
tile[x][y] = 0;
}
}