> For the complete documentation index, see [llms.txt](https://guide.cronuszen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guide.cronuszen.com/gpcscripting/gpc-script-guide/start-here/first-mistakes-to-recognize.md).

# First mistakes to recognize

### Declaring inside a block

```cpp
main {
    int value;  // invalid: runtime variables must be top-level
}
```

Move `int value;` above `init` / `main`.

***

### Confusing assignment and comparison

```cpp
if(mode = 2) { }   // assigns 2; the condition is then true
if(mode == 2) { }  // compares; usually what was intended
```

Zen Studio Live warns about assignment in a condition, but write the intended operator.

***

### Using the wrong letter case

`PS5_CROSS`, `ps5_cross`, and `PS5_Cross` are different names. Only the defined constant is valid.

***

### Assuming a function changes its caller's variable

Function arguments are values held in local parameters:

```cpp
int amount = 10;

main {
    amount = add_five(amount);  // store the returned value
}

function add_five(value) {
    value = value + 5;
    return value;
}
```

***

### Writing forever in an inner loop

```cpp
while(TRUE) { }  // do not do this in live real-time code
```

`main` is already the repeating loop. Inner loops should complete quickly and have an obvious bound.


---

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