26
votes
How to solve "control may reach end of non void function" error
This problem comes from a misunderstanding of the flow of control in your algorithm. Here's a representation of that control flow in pseudocode:
if (outer-condition-1)
if (inner-condition-1)
...
- 2,146
8
votes
Where can I find 3x3.txt?
First, run update50 to make sure you are up to date. Run appliance50 to verify that you have version 19-2.
Then, run ls ~cs50/pset3
You should see the files there.
As a last resort, download ...
- 18.4k
5
votes
Why Aren't My Last Two Tiles Swapping?
Recall that arrays are zero based. So if you have an array of d elements, the index goes from 0 to d - 1.
- 2,625
4
votes
Accepted
Fifteen move not working in last row only
A very common problem. Look at the following:
else if (i < d && board[i + 1][j] == 0)
This code attempts to swap with a tile that is off the edge of the board. If i = d-1, then what is ...
- 64.6k
3
votes
Accepted
Pset 3: Fifteen - Moving up and down but not left or right?
So, it was a subtle problem and an easy mistake to make. Look at the limits on your 4 conditions: > 0 and < d. >0 works because it allows for swapping to array elements with 0 as an index. ...
- 64.6k
3
votes
Accepted
move function, pset3
Well, I don't know how to tell you this, but I plugged your move function into my code and it worked perfectly. I suspect that you have a problem elsewhere in your code. Have you altered something in ...
- 64.6k
3
votes
pset 3 "control may reach the end of a non-void function"
Your function is declared as having a return type, but the structure of your function is not guaranteed to return anything.
For example, if you have:
bool myfunction(int x)
{
if(x > 10)
{...
- 182
3
votes
Accepted
PSET 3: Game of fifteen. Everything in the board is equal to zero
You only need to delete this and the code will work:
int board[d][d];
The reason is that the global variable board is declared above and can be used by any function
int board[DIM_MAX][DIM_MAX];
...
- 1,139
3
votes
A wierd error in won function (fifteen)
the hint is in
1-2-3|4-5-6|0-7-8
ie
1 2 3
4 5 6
0 7 8
Your won function will say that's a winning position, which it isn't.
That same sort of scenario doesn't occur during the 4x4 gameplay.
To ...
- 18.4k
2
votes
How to pass grid values to draw in pset3
The board was already declared for you as a global array, so you should be setting the initial values in your init() and then drawing that array in your draw(). The draw() function is also called ...
- 18.4k
2
votes
Accepted
Swap 2 and 1 after looping, pset3, Game of Fifteen
Don't you want to swap the two tiles? You are swapping 2 new integers that happen to hold the tile values.
Get rid of those 2 extra integers and simply use the tiles themselves in your swap code.
...
- 18.4k
2
votes
Global variables to store the position of the blank space?
Declare hori and verti as global variables and initialize them to d - 1 just after init().
- 171
2
votes
Accepted
All my moves entered are shown illegal, though code doesn't seem wrong... (PS3 - fifteen)
The thing is:
The program has declared a global variable d already.
//board dimension
int d;
In your program, there's another declaration of d, in your a b c d initialisation.
Thus, your for ...
- 36
2
votes
Accepted
pset 3 - game of fifteen - move tile
It looks like you didn't account for the corner cases where the blank is on the edge of the board. In other words, when you try to swap, i or j could go out of range, essentially swapping with ...
- 64.6k
2
votes
Accepted
pset3 fifteen's draw function problem
I just tested your code and got it working with a couple minor tweaks. My advice is to go look back at your global variables. Something you have in both those functions has been declared earlier in ...
- 1,424
2
votes
What is if(!move(tile)) and can I change it?
if (!move(tile)) is a shortcut for
bool didItMove = move(tile);
if (didItMove == false)
{
// do this
}
In other words, it first calls the move function (that you are writing), passing in the tile ...
- 18.4k
2
votes
Accepted
Pset3: strange problem while testing init() function
When you declare an array, such as board, you want to use the actual size of the array, without subtracting 1.
- 188
2
votes
Accepted
pset3 fifteen - how to check if tile is adjacent to 0/"_"?
Simply put, if tile is in board[i][j], you need to check the positions directly above, below, and on either side for 0. In other words, board[i+1][j], board[i-1][j], board[i][j+1], board[i][j-1].
But ...
- 64.6k
2
votes
Accepted
pset3 fifteen adjacent check not working
It fails because 3 out of 4 of your if conditions are wrong.
- 64.6k
2
votes
Accepted
Pset3 Fifteen Check50 not Working
Wow, this is something I've never seen before. Congratulations! ;-) Your code is both right and wrong at the same time! :-D
Yes, your code displays correctly and looks perfectly correct. It also ...
- 64.6k
2
votes
Accepted
Pset3 Fifteen: Draw and/or Init Function Problem
You cannot check if number is even with if (d/2 == 0)
use % sign (remainder sign).
Number is even if you divide the number with 2 and remainder becomes 0.
for example
if (d%2 == 0)
{
//...
- 549
2
votes
Accepted
Am I going about Init() correctly?
It looks good (not a guarantee) right up until the end. What do you think will happen when you try to assign a string to an int?
Instead, leave the 0 in place for the blank tile here, and use the ...
- 64.6k
2
votes
Accepted
Error in dependency - pset3 fifteen
Assuming it does compile, the move function has a couple of serious flaws. First, given the math used, the tests should be comparing to d, not d-1. This error is preventing anything on the right side ...
- 64.6k
2
votes
Pset3/Fifteen/Init Function - Problem with 1 and 2 swap
Actually, the swap shouldn't be inside any for loop. You only want to do the swap once. Putting it inside any loop does it multiple times. Since the swap only depends on the value of d, and nothing ...
- 64.6k
2
votes
PSET3 Game of Fifteen move() Problem
To check if a tile is adjacent to the tile the user requested to move to with indices you simply use an if statement with the condition you wish to check for, which is then followed by something like ...
- 1,223
2
votes
Accepted
PSET3 Game of Fifteen move() Problem
@M.Kleiven's tips are interesting, but I just looked at my solution, and I did not need to use pointers to check if a tile is outside the board. Here's what I did, in pseudo-code:
// initialize board ...
- 3,036
2
votes
Fifteen: Error in a function I haven't touched yet
I couldn't find anything about this and I ended solving the problem a few minutes after posting the question: for some reason, the MakeFile file had been wiped out and was empty. I uploaded the ...
2
votes
Accepted
pset3: Help with Fifteen Move function
I think it's ok to search for both tile and empty tile, though you could maintain global variable(s) to store the position of the empty tile, some even keep track of the positions of all tiles, ...
- 20.7k
2
votes
Accepted
Pset3 - Game of Fifteen - init function
You use local stack variable for the board, local variables will be deleted on leaving the function, should probably use a global variable. Local variables of same name shadow global ones (compiler ...
- 20.7k
2
votes
Accepted
Game of Fifteen pset3 - won() function works, but why?
Think about what happens in various scenarios. First, the first if test checks that 0 is in the last tile. If it isn't, the code returns false, so from there on, 0 must be in the last tile. Keep this ...
- 64.6k
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