Why is this j considered an undeclared identifier when it's declared - c

Question

The j in the printing statement is considered an undeclared identifier, how do I fix this?
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++)
switch(grid[i][j]){
case '.':
colourChange(WHITE);
break;
case 'P':
colourChange(YELLOW);
break;
case 'G':
colourChange(PINK);
break;
case 'W':
colourChange(BLUE);
break;}
printf("%c ", grid[i][j]);
printf("\n");
}
I declared it in the for loop, but it gave an error. Also if I comment out the full switch statement it works.

Answer 1

The body of the inner for loop is just the switch statement, so the call to printf that follows is outside of the inner loop.
Always use braces:
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
switch(grid[i][j]) {
case '.':
colourChange(WHITE);
break;
case 'P':
colourChange(YELLOW);
break;
case 'G':
colourChange(PINK);
break;
case 'W':
colourChange(BLUE);
break;
}
printf("%c ", grid[i][j]);
}
printf("\n");
}

Answer 2

This is because your second for statement. Since it has no curly braces, it assumes the next statement corresponds to its body. Your following printf("%c ", grid[i][j]); assumes that there is no j to take into account and is not recognized. A fixed solution may be:
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
switch(grid[i][j]) {
case '.':
colourChange(WHITE);
break;
case 'P':
colourChange(YELLOW);
break;
case 'G':
colourChange(PINK);
break;
case 'W':
colourChange(BLUE);
break;
}
printf("%c ", grid[i][j]);
}
printf("\n");
}