CMC never shows you a scary wall of gibberish. Every mistake looks like this:
OOGA! Line 7: There is no box named 'rocks'.
Hint: make it first with: grunk rocks = ...Two lines: what went wrong, and how to fix it. That is all.
Reading an error
- OOGA! -- a mistake happened. Nobody is in trouble.
- Line 7 -- the line to look at. In OGABOOGA CODER you can see line
numbers in the gutter next to the code.
- Hint -- the friendly fix.
The mistakes everyone meets
Blocks
| Message | What happened |
|---|---|
A block was opened but never closed. | you forgot an unga |
You said 'unga', but nothing was open for it to close. | one unga too many |
Count your blocks. Every binga, booga, zug, zoop, and clump needs exactly one unga.
Boxes
| Message | What happened |
|---|---|
There is no box named 'x'. | use before grunk, or a typo |
There is no box named 'x' to put that into. | x = ... before making the box |
'nom' already means something in CMC | pick a different name |
Text and numbers
| Message | What happened |
|---|---|
Text and numbers cannot be stuck together directly. | use goop(7) |
numba cannot turn "banana" into a number. | the answer was not a number |
Cannot share by zero! | someone divided by 0 |
I can only line up numbers with numbers, or text with text | < between kinds |
Piles
| Message | What happened |
|---|---|
There is no spot 9 in that pile (it has 3 spots). | spot numbers start at 0 |
The pile is empty, so there is nothing to yoink! | check nom(pile) > 0 |
'zoop' walks through piles and text | you gave it a number |
Clumps
| Message | What happened |
|---|---|
'add' wants 2 things, but got 3. | check the parentheses |
There is no clump named 'gret'. | typo, or define it first |
'x' is a box, not a clump | remove the () or rename |
'ork' can only live inside a clump. | move it inside a clump block |
Runaways
| Message | What happened |
|---|---|
This program ran for a very long time. Maybe a loop never stops? | a zug check never becomes nork |
called itself too many times and went too deep. | recursion without a stopping binga |
The three step fix
- Read the line number. Go there.
- Read the hint. It usually names the exact word to add.
- Change one thing and run again. Small steps are fastest.
If you get stuck, delete the last thing you added. The bug is almost always there.
Errors are nothing to fear
Every programmer in the world sees errors all day. In CMC they even have a name: OOGA. Collect them. Each one teaches you one thing the computer needs.
Next: English mode.