boost::urls::url::set_host :: Boost Libraries Documentation

# boost::urls::url::set_host

Set the host

## Synopsis

Declared in `<boost/url/url.hpp>`

    url&
    set_host(core::string_view s);

## Description

Depending on the contents of the passed string, this function sets the host:

- If the string is a valid IPv4 address, then the host is set to the address. The host type is `host_type::ipv4`.

- If the string is a valid IPv6 address enclosed in square brackets, then the host is set to that address. The host type is `host_type::ipv6`.

- If the string is a valid IPvFuture address enclosed in square brackets, then the host is set to that address. The host type is `host_type::ipvfuture`.

- Otherwise, the host name is set to the string, which may be empty. Reserved characters in the string are percent‐escaped in the result. The host type is `host_type::name`.

In all cases, when this function returns, the URL contains an authority.

## Example

    assert( url( "http://www.example.com" ).set_host( "127.0.0.1" ).buffer() == "http://127.0.0.1" );

## Postconditions

    this->has_authority() == true

## Complexity

Linear in `this‐>size() + s.size()`.

## Exception Safety

Strong guarantee. Calls to allocate may throw.

## BNF

    host        = IP-literal / IPv4address / reg-name

    IP-literal  = "[" ( IPv6address / IPvFuture  ) "]"

    reg-name    = *( unreserved / pct-encoded / "-" / ".")

## Specification

- IPv4 (Wikipedia)

- IP Version 6 Addressing Architecture (rfc4291)

- 3.2.2. Host (rfc3986)

## Return Value

`*this`

## Parameters

Name | Description
s | The string to set.

## See Also

`set_encoded_host`, `set_encoded_host_address`, `set_encoded_host_name`, `set_host_address`, `set_host_ipv4`, `set_host_ipv6`, `set_host_ipvfuture`, `set_host_name`.

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