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# QHostInfo Class Reference
[com.trolltech.qt.network module]

The `QHostInfo` class provides static functions for host name lookups. More...

## Detailed Description

The `QHostInfo` class provides static functions for host name lookups.

`QHostInfo` uses the lookup mechanisms provided by the operating system to find the IP address(es) associated with a host name, or the host name associated with an IP address. The class provides two static convenience functions: one that works asynchronously and emits a signal once the host is found, and one that blocks and returns a `QHostInfo` object.

To look up a host's IP addresses asynchronously, call lookupHost(), which takes the host name or IP address, a receiver object, and a slot signature as arguments and returns an ID. You can abort the lookup by calling `abortHostLookup` with the lookup ID.

Example:

        // To find the IP address of www.trolltech.com
        QHostInfo::lookupHost("www.trolltech.com",
                              this, SLOT(printResults(QHostInfo)));

        // To find the host name for 4.2.2.1
        QHostInfo::lookupHost("4.2.2.1",
                              this, SLOT(printResults(QHostInfo)));

The slot is invoked when the results are ready. (If you use Qtopia Core and disabled multithread support by defining `QT_NO_THREAD`, lookupHost() will block until the lookup has finished.) The results are stored in a `QHostInfo` object. Call `addresses` to get the list of IP addresses for the host, and `hostName` to get the host name that was looked up.

If the lookup failed, `error` returns the type of error that occurred. `errorString` gives a human-readable description of the lookup error.

If you want a blocking lookup, use the QHostInfo::fromName() function:

        QHostInfo info = QHostInfo::fromName("www.trolltech.com");

`QHostInfo` supports Internationalized Domain Names (IDNs) through the IDNA and Punycode standards.

To retrieve the name of the local host, use the static QHostInfo::localHostName() function.

See also `QAbstractSocket` and RFC 3492.