# lv_check_arg.h (/api/public/debugging/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_ASSERT_HANDLER_ [#lv_check_arg_assert_handler_]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG_ASSERT_HANDLER_ do {} while(0)
```
LV_CHECK_ARG_LOG_ [#lv_check_arg_log_]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG_LOG_(cond_str, msg) \
do {} while(0)
```
LV_CHECK_ARG_LOG_FORMAT_ [#lv_check_arg_log_format_]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG_LOG_FORMAT_(cond_str, format, ...) \
do {} while(0)
```
LV_CHECK_ARG_INTERNAL_ [#lv_check_arg_internal_]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG_INTERNAL_(cond, cond_str, action_on_fail, msg) \
if(LV_UNLIKELY(!(cond))) { \
LV_CHECK_ARG_LOG_(cond_str, msg); \
LV_CHECK_ARG_ASSERT_HANDLER_; \
action_on_fail; \
} else {}
```
LV_CHECK_ARG_FORMAT_INTERNAL_ [#lv_check_arg_format_internal_]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG_FORMAT_INTERNAL_(cond, cond_str, action_on_fail, format, ...) \
if(LV_UNLIKELY(!(cond))) { \
LV_CHECK_ARG_LOG_FORMAT_(cond_str, format, __VA_ARGS__); \
LV_CHECK_ARG_ASSERT_HANDLER_; \
action_on_fail; \
} else {}
```
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, "")
```
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`).
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. Log output requires LV\_USE\_LOG to be enabled; if LV\_USE\_LOG is 0 no output is produced regardless of LV\_CHECK\_ARG\_LOG\_MODE.
Example:
```c title=" " lineNumbers=1
LV_CHECK_ARG(ptr != NULL, return);
```
Parameters
| Name | Description |
| ---------------- | -------------------------------------------------------------------- |
| `cond` | condition to check |
| `action_on_fail` | statement to execute on failure (e.g. `return`, `return 0`, `break`) |
LV_CHECK_ARG_MSG [#lv_check_arg_msg]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG_MSG(cond, action_on_fail, msg) \
LV_CHECK_ARG_INTERNAL_(cond, #cond, action_on_fail, " " msg)
```
Same as LV\_CHECK\_ARG but a message is appended to the log. The message is only used when LV\_CHECK\_ARG\_LOG\_MODE is set to VERBOSE.
Example:
```c title=" " lineNumbers=1
LV_CHECK_ARG_MSG(ptr != NULL, return, "pointer must not be NULL");
```
Parameters
| Name | Description |
| ---------------- | -------------------------------------------------------------------- |
| `cond` | condition to check |
| `action_on_fail` | statement to execute on failure (e.g. `return`, `return 0`, `break`) |
| `msg` | string literal appended to the log message |
LV_CHECK_ARG_FORMAT_MSG [#lv_check_arg_format_msg]
```c title=" " lineNumbers=1
#define LV_CHECK_ARG_FORMAT_MSG(cond, action_on_fail, format, ...) \
LV_CHECK_ARG_FORMAT_INTERNAL_(cond, #cond, action_on_fail, " " format, __VA_ARGS__)
```
Same as LV\_CHECK\_ARG but a printf-style message is appended to the log. The message is only used when LV\_CHECK\_ARG\_LOG\_MODE is set to VERBOSE.
Example:
```c title=" " lineNumbers=1
LV_CHECK_ARG_FORMAT_MSG(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`) |
| `format` | format string literal appended to the log message |
| `...` | arguments of `format`; at least one is required |
Dependencies [#dependencies]