How can I do this again? in C - c

Question

#define G 10
int main(){
int grid[G][G],c,x;
for(c=1;c<=5;c++){
for(x=1;x<=5;x++){
if(c+x<=5)
grid[c][x]=+1;
else if(c+x>=7)
grid[c][x]=-1;
else
grid[c][x]=0;
printf("%2d\t ",grid[c][x]);
}
printf("\n");
}
getch();
return 0;
}
its output is
Which is what I really wanted to do but now I need to make it look like
and now I don't have any idea on how to do it, it's hurting my head now

Answer 1

I would do it like this
for(c=0; c<5; c++) { /* arrays start at 0, not 1. */
for(x=0; x<5; x++) { /* arrays start at 0, not 1. */
if (c == x) { /* looking at your output, the 0's occur when c == x */
grid[c][x] = 0;
} else if (c > x) { /* the -1 when c > x */
grid[c][x] = -1;
} else { /* obviously c > x */
grid[c][x] = 1;
}
/* nothing else changed */
printf("%2d\t ",grid[c][x]);
}
printf("\n");
}

Answer 2

It's quite simple, you have three distinct cases:
if both c and x are equal, your grid shows zero
if x is greater than c, your grid shows 1
else (ie, when x is less than c), your grid shows -1
Basically, we've written the if-else structure you need in your loop to get the desired output:
if (c == x) grid[c][x] = 0;
else if (x > c) grid[c][x] = 1;
else grid[c][x] = -1;
Thus, the full code looks like this:
#include <stdio.h>
#define G 10
int main()
{
int grid[G][G],c,x;
for(c=0;c<5;++c)
{//zero indexed
for(x=0;x<5;++x)
{//perhaps change 5 with G, or another macro or some int
if(c == x) grid[c][x] = 0;
else if (c < x) grid[c][x] = 1;//1 is fine, the + is not required
else grid[c][x] = -1;
printf("%2d\t ",grid[c][x]);
}
printf("\n");
}
return 0;
}
Which as you can see on this codepad works just fine.
note:
As I said, the + in +1 is optional. I'd even advise against it. If I happen to come across a statement like some_int = +1; I might assume that it's a bug, and it was supposed to read some_int += 1;, which is a different thing all together.

Answer 3

The major diagonal of matrix is collection of elements that meet row==column condition. Plus we know that row and column elements above(right from) diagonal meet row<column, and below ones row>column condition. And here is how to make that matrix and while making we will show them :
#define G 5
int grid[G][G], row, column;
for (row =0; row < G; row++) {
for (column =0; column < G; column++) {
if (row<column)
grid[row][column] = 1;
else if (row>column)
grid[row][column] = -1;
else
grid[row][column] = 0;
printf("%2d\t ", grid[row][column]);
}
printf("\n");
}
And here is output:
0 1 1 1 1
-1 0 1 1 1
-1 -1 0 1 1
-1 -1 -1 0 1
-1 -1 -1 -1 0
And Here is what was your problem.
You chose minor (secondary) diagonal isntead of main
Your index handling done manually .Like you calculated conditions manually. It is not good
And here is how you should do for minor diagonal without calculating condition manually
#define G 5
int grid[G][G], row, column ;
for(row=0;row<G;row++){
for(column=0;column< G;column++){
if(row+column<G-1)
grid[row][column]=1;
else if(row+column>G-1)
grid[row][column]=-1;
else /*minor diagonal meet row==(G-1)-column //G-1 cause index begins from 0*/
grid[row][column]=0;
printf("%2d\t ",grid[row][column]);
}
printf("\n");
}

Answer 4

Now Swap the first and last columns of your matrix then second and second last. Thats it

Answer 5

#include <stdio.h>
#define G 10
int i,j;
int grid[G][G];
int main() {
for(i=0; i<G; i++) {
for(j=0; j<G; j++) {
if(i==j) grid[i][j]=0;
else if(i<j) grid[i][j]=1;
else if(i>j) grid[i][j]=-1;
printf("%2d\t", grid[i][j]);
}
printf("\n");
}
return 0;
}

Answer 6

you can modify your program as below :
1,for(c=1;c<=5;c++) -->for(c=5;c>=1;c--)
2, grid[c][x]=+1; --> grid[c][x]=-1;
3, grid[c][x]=1; --> grid[c][x]=+1;
#define G 10
int main(){
int grid[G][G],c,x;
for(c=5;c>=1;c--){
for(x=1;x<=5;x++){
if(c+x<=5)
grid[c][x]=-1;
else if(c+x>=7)
grid[c][x]= 1;
else
grid[c][x]=0;
printf("%2d\t ",grid[c][x]);
}
printf("\n");
}
getch();
return 0;
}

Answer 7

You need to create a 2D matrix, where the matrix is diagonally zero, upper triangle would be 1, and lower triangle would be -1.
So,
if **row == column** , then assign 0 to diagonal. (**grid[row][column] = 0**)
else if , **row < column**, then assign 1 to upper triangle. (*grid[row][column*] = 1)
else, **row > column**, then assign -1 to lower triangle. (*grid[row][column] = -1*)