Accessing windows registry in C#

Question

I am trying to get all the SQL Instances installed on a local machine with the help of following code:

RegistryKey rk = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Microsoft SQL Server");
string[] instances = (string[])rk.GetValue("InstalledInstances");

if (instances.Length > 0)    //Error
{
    foreach (string instance in instances)
    {
        MessageBox.Show(instance);
    }
}

It is giving the following exception:

Object reference not set to an instance of an object.

I've manually checked the 'Registry-Editor' and the specified keys exist, also there are two SQL Instances on my system.

Now please tell me why it is not accessing the required key value?

See this [SO Question](http://stackoverflow.com/questions/6799584/accessing-registry-on-windows-7-c-sharp?rq=1) — Mark Hall, Jul 06 '12 at 00:15
But "InstalledInstances" does not exist under "Microsoft SQL Server" key. — Muhammad Ali, Jul 06 '12 at 00:23

score 0 · Answer 1 · answered Jul 06 '12 at 00:24

0

This line could be the issue string[] instances = (string[])rk.GetValue("InstalledInstances");

Because RegistryKey.GetValue Method (String) returns a object and you are casting that in to string[]

before casting it to string[] you should check if the returned value is not null

answered Jul 06 '12 at 00:24

HatSoft

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I don't think this answer is correct because if GetValue returned null then the cast to string[] would cause an error, since you can't cast a null value into a string array. His error seems to occur after this though, which tells me its not returning null and its successfully casting to a string array. – Icemanind Jul 06 '12 at 01:04

score 0 · Accepted Answer · answered Jul 06 '12 at 04:09

0

I ran your code on my 64-bit machine. It worked fine. Make sure you platform is set to AnyCPU or x64 but not x86

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answered Jul 06 '12 at 04:09

Harvey Kwok

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Accessing windows registry in C#

2 Answers2