# lv_check_arg.h (/api/misc/lv_check_arg_h)
Macros [#macros]
LV_LIKELY [#lv_likely]
```c title=" " lineNumbers=1
#define LV_LIKELY(x) \
(x)
```
LV_UNLIKELY [#lv_unlikely]
```c title=" " lineNumbers=1
#define LV_UNLIKELY(x) \
(x)
```
LV_CHECK_ARG_INTERNAL_ [#lv_check_arg_internal_]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG_INTERNAL_(cond, cond_str, action_on_fail, ...) \
if(LV_UNLIKELY(!(cond))) { \
LV_LOG_WARN("Check failed: " cond_str " " __VA_ARGS__); \
action_on_fail; \
} else {}
```
Internal macro: checks a condition, logs a warning, and executes the specified action on failure. Do not use directly; use LV\_CHECK\_ARG instead.
LV_CHECK_ARG [#lv_check_arg]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG(cond, action_on_fail, ...) \
LV_CHECK_ARG_INTERNAL_(cond, #cond, action_on_fail, __VA_ARGS__)
```
Check that a condition is true. If the condition is false, log a warning and execute `action_on_fail` (e.g. `return`, `return val`, `break`). Additional printf-style arguments are appended to the log message.
Can be disabled entirely by setting LV\_USE\_CHECK\_ARG to 0 in lv\_conf.h. If LV\_CHECK\_ARG\_ASSERT\_ON\_FAIL is 1, LV\_ASSERT\_HANDLER is also invoked before the action.
Example:
```c title=" " lineNumbers=1
LV_CHECK_ARG(ptr != NULL, return, "pointer must not be NULL");
LV_CHECK_ARG(len > 0, return -1, "len=%d", (int)len);
```
Parameters
| Name | Description |
| ---------------- | --------------------------------------------------------------------- |
| `cond` | condition to check |
| `action_on_fail` | statement to execute on failure (e.g. `return`, `return 0`, `break`) |
| `...` | optional printf-style format string and arguments appended to the log |
Dependencies [#dependencies]