Details
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PHP Version 5.5.12
Compiler MSVC11 (Visual C++ 2012)
Architecture x64
mongodb driver: php_mongo-1.5.7-5.5-vc11-x86_64.dll
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Please give example how to connect to mongodb

I try this:
$m = new MongoClient ("mongodb://$user:$pass@{$host}:{$port}");

Or this:
$m = new MongoClient ("mongodb://{$host}:{$port}",[
'username' => $user,
'password' => $pass
]);

Error I have got:
Failed to connect to: localhost:27017: SASL Authentication failed on database 'admin': Authentication failed.