main/syscalls/counter_read.md

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# zx_counter_read

## Summary

Read the value of a counter.

## Declaration

```c
#include <zircon/syscalls.h>

zx_status_t zx_counter_read(zx_handle_t handle, int64_t* value);
```

## Description

`zx_counter_read()` reads the value of the counter referenced by *handle* into
the integer *value* points at.

## Rights

*handle* must have `ZX_RIGHT_READ`.

## Return value

`zx_counter_read()` returns `ZX_OK` on success.

On failure, an error value is returned.

## Errors

`ZX_ERR_WRONG_TYPE`  if *handle* is not a counter handle.

`ZX_ERR_ACCESS_DENIED`  if *handle* does not have `ZX_RIGHT_READ`.

`ZX_ERR_INVALID_ARGS`  if *value* is an invalid pointer.

## See also

 - [`zx_counter_create()`]
 - [`zx_counter_add()`]
 - [`zx_counter_write()`]

[`zx_counter_create()`]: counter_create.md
[`zx_counter_add()`]: counter_add.md
[`zx_counter_write()`]: counter_write.md