Declaring variable inside If

Graeme Pariot

12y1.3kLearn iOS Programming

Hi,

I did many times but not able to declare variable in side my IF-ELSE. Please tell me where I am making a mistake.

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Shweta Lodha12y ago
Accepted answer
Hello Graeme Pariot,
As per .Net, you can not declare variable inside IF condition. That's the reason you are facing an error. To get rid of this error, please declare your variable outside IF and then use that inside IF condition. That will work.

Bit more info: Reason behind this is that IF expects an expression, not a statement. If you wanna know more, check this link:
http://msdn.microsoft.com/en-us/library/aa664742(v=vs.71).aspx
Vulpes12y ago
No, but the first correct answer (i.e. Shweta's) should be given the accolade which is what you've done :)

As a correct answer had already been posted, I only posted myself to add something which I thought might be of interest to you or other members reading the thread.
Graeme Pariot12y ago
Is there a way to mark two posts as answered ?
Vulpes12y ago
It depends whether you're talking about declaring variables inside the condition or the body of the 'if' statement.

If you're talking about the condition, then you simply can't do it as Shweta said.

However, you CAN declare variables in the body of an 'if' statement. The only restriction is that they must not have the same name as local variables declared in an 'outer' scope because there would be no way to access the latter if this were allowed.

So, this program compiles and works fine:

using System;

class Program
{
static void Main()
{
int i = 0, j = 0;

if (i == 0)
{
// this compiles and works fine
int k = 1;
Console.WriteLine(k);
Console.WriteLine(j);
}

/*
if (i != 1)
{
// this doesn't compile because the 'outer' j
// would no longer be accessible
int j = 1;
Console.WriteLine();
}
*/

Console.ReadKey();
}
}

However, if you uncomment the second 'if' statement, then it won't compile because the 'j' which is local to the 'if' statement would conflict with the 'j' which is local to the method as a whole.