# PR_SendTo

Sends bytes a socket to a specified destination.

## Syntax

```{code}
#include <prio.h>

PRInt32 PR_SendTo(
  PRFileDesc *fd,
  const void *buf,
  PRInt32 amount,
  PRIntn flags,
  const PRNetAddr *addr,
  PRIntervalTime timeout);
```

### Parameters

The function has the following parameters:

`fd`

: A pointer to a {ref}`PRFileDesc` object representing a socket.

`buf`

: A pointer to a buffer containing the data to be sent.

`amount`

: The size of `buf` (in bytes).

`flags`

: This obsolete parameter must always be zero.

`addr`

: A pointer to the address of the destination.

`timeout`

: A value of type {ref}`PRIntervalTime` specifying the time limit for
  completion of the receive operation.

### Returns

The function returns one of the following values:

- A positive number indicates the number of bytes successfully sent.
- The value -1 indicates a failure. The reason for the failure can be
  obtained by calling {ref}`PR_GetError`.

## Description

{ref}`PR_SendTo` sends a specified number of bytes from a socket to the
specified destination address. The calling thread blocks until all bytes
are sent, a timeout has occurred, or there is an error.