pr_getprotobynumber.md

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# PR_GetProtoByNumber

Looks up a protocol entry based on protocol's number.

## Syntax

```{code}

#include <prnetdb.h>

PRStatus PR_GetProtoByNumber(

  PRInt32 protocolnumber,

  char* buffer,

  PRInt32 bufsize,

  PRProtoEnt* result);

```

### Parameters

The function has the following parameters:

`protocolnumber`

: The number assigned to the protocol.

`buffer`

: A pointer to a scratch buffer for the runtime to return result. This

  buffer is allocated by the caller.

`bufsize`

: Number of bytes in the `buffer` parameter. The buffer must be at

  least {ref}`PR_NETDB_BUF_SIZE` bytes.

`result`

: On input, a pointer to a {ref}`PRNetAddr` structure. On output, this

  structure is filled in by the runtime if the function returns

  `PR_SUCCESS`.

### Returns

The function returns one of the following values:

- If successful, `PR_SUCCESS`.

- If unsuccessful, `PR_FAILURE`. You can retrieve the reason for the

  failure by calling {ref}`PR_GetError`.