Matrices and coordinate system - arrays

Question

How can I draw the function x+y=n with n not greater than 10 and the coordinate system using only matrices without any functions or libraries? I am a beginner and I hope you could help me.The only problem is that my code prints spaces above the line x+y=n and it should not.
#include <stdio.h>
int
main()
{
int n, i, j;
scanf("%d", &n);
char m[12][63] = { " " };
for (i = 0; i < 12; i++) {
for (j = 0; j < 63; j++) {
m[i][j] = ' ';
if (i == 0 && j == 1)
m[i][j] = '0';
if (i == 11 && j == 61)
m[i][j] = '2';
if (j == 0 && i != 0 && i != 11)
m[i][j] = '0' + 10 - i;
if (j == 2 && i != 11)
m[i][j] = '+';
if (i == 11 && j % 3 == 2)
m[i][j] = '0' + ((j - 2) / 3) % 10;
if (i == 11 && j % 3 == 1 && j > 29 && j < 59)
m[i][j] = '1';
if (i == 10 && j % 3 == 2)
m[i][j] = '+';
}
}
for(i=1;i<n+1;i++){
if((10-n+i)!=10 && (2+3*i)!=1)
m[10-n+i][2+3*i]='*';
}
m[0][0]='1';
for (i = 0; i < 12; i++) {
for (j = 0; j < 63; j++) {
printf("%c", m[i][j]);
}
printf("\n");
}
}
//n=5
10+
9 +
8 +
7 +
6 +
5 +
4 + *
3 + *
2 + *
1 + *
0 + + + + + + + + + + + + + + + + + + + + +
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Answer 1

So first of all its quite difficult for me to understand your logic behind the if statements in the for loop.
With that said, to get the desired 10+ on the y-axis i set m[0][0] = '1'; which seems to work.
As for drawing the line, it seems that:
if (j == 3 * (n + i - 10) && i > 2 && j > 2) m[i][j] = '*';
was causing the issues. I replaced it with:
m[10 - n][2] = '*';
for (i = 1; i < n+1; i++)
{
m[10 - n + i][2 + 3 * i] = '*';
}
and it works fine and in a more understandable way hopefully!
So in the end the code should look like this:
#include<stdio.h>
int main()
{
int n, i, j;
scanf("%d", &n);
char m[12][63] = { " " };
for (i = 0; i < 12; i++) {
for (j = 0; j < 63; j++) {
m[i][j] = ' ';
if (i == 0 && j == 1) m[i][j] = '0';
if (i == 11 && j == 61) m[i][j] = '2';
if (j == 0 && i != 0 && i != 11) m[i][j] = '0' + 10 - i;
if (j == 2 && i != 11) m[i][j] = '+';
if (i == 11 && j % 3 == 2) m[i][j] = '0' + ((j - 2) / 3) % 10;
if (i == 11 && j % 3 == 1 && j > 29 && j < 59) m[i][j] = '1';
if (i == 10 && j % 3 == 2) m[i][j] = '+';
// if (j == 3 * (n + i - 10) && i > 2 && j > 2) m[i][j] = '*';
}
}
m[10 - n][2] = '*'; // sets + on y-axis to *
for (i = 1; i < n+1; i++)
{
m[10 - n + i][2 + 3 * i] = '*'; // draws * diagonally jumping 3 characters (thus 3*i)
}
m[0][0] = '1'; // to have 10 instead of 0 at the top left
for (i = 0; i < 12; i++) {
for (j = 0; j < 63; j++) {
printf("%c", m[i][j]);
} printf("\n");
}
}
For n=7 for example you get the desired:
10+
9 +
8 +
7 *
6 + *
5 + *
4 + *
3 + *
2 + *
1 + *
0 + + + + + + + * + + + + + + + + + + + + +
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
To not delete the + by the * just offset the line to the right:
m[10 - n][3] = '*';
for (i = 1; i < n+1 ; i++)
{
m[10 - n + i ][3 + 3 * i] = '*'; // draws * diagonally jumping 3 characters (thus 3*i)
}
m[0][0] = '1'; // to have 10 instead of 0 at the top left
So the n=7 example should now look:
10+
9 +
8 +
7 +*
6 + *
5 + *
4 + *
3 + *
2 + *
1 + *
0 + + + + + + + +* + + + + + + + + + + + + +
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
In order to not print chars above or after the line try this:
#include <stdio.h>
int main()
{
int n, i, j;
scanf("%d", &n);
char m[12][63] = { " " };
for (i = 0; i < 12; i++) {
for (j = 0; j < 63; j++) {
m[i][j] = ' ';
if (i == 0 && j == 1)
m[i][j] = '0';
if (i == 11 && j == 61)
m[i][j] = '2';
if (j == 0 && i != 0 && i != 11)
m[i][j] = '0' + 10 - i;
if (j == 2 && i != 11)
m[i][j] = '+';
if (i == 11 && j % 3 == 2)
m[i][j] = '0' + ((j - 2) / 3) % 10;
if (i == 11 && j % 3 == 1 && j > 29 && j < 59)
m[i][j] = '1';
if (i == 10 && j % 3 == 2)
m[i][j] = '+';
}
}
for (i = 1; i < n + 1; i++) {
if ((10 - n + i) != 10 && (2 + 3 * i) != 1)
m[10 - n + i][2 + 3 * i] = '*';
}
m[0][0] = '1';
for (i = 0; i < 12; i++)
{
for (j = 0; j < 63; j++)
{
if ((i < 10 - n) || (j > 2 + 3 * n))
{
m[i][j] = '\0';
}
}
}
for (i = 0; i < 12; i++) {
for (j = 0; j < 63; j++) {
printf("%c", m[i][j]);
}
printf("\n");
}
}
and for n=5 you get:
5 +
4 + *
3 + *
2 + *
1 + *
0 + + + + + +
0 1 2 3 4 5
Hope this helps!