What does the “private” modifier do?

Question

Considering "private" is the default access modifier for class Members, why is the keyword even needed?

Answer 1

As pointed out by Jon Skeet in his book C# In Depth, there is one place in C# where the private keyword is required to achieve an effect.

If my memory serves correctly, the private keyword is the only way to create a privately scoped property getter or setter, when its opposite has greater than private accessibility. Example:

public bool CanAccessTheMissileCodes
{
    get { return canAccessTheMissileCodes; }
    private set { canAccessTheMissileCodes = value; }
}

The private keyword is required to achieve this, because an additional property accessability modifier can only narrow the scope, not widen it. (Otherwise, one might have been able to create a private (by default) property and then add a public modifier.)

Answer 2

Some coding styles recommend that you put all the "public" items first, followed by the "private" items. Without a "private" keyword, you couldn't do it that way around.

Update: I didn't notice the "c#" tag on this so my answer applies more to C++ than to C#.

Answer 3

Using private explicitly signals your intention and leaves clues for others who will support your code ;)

Answer 4

It's for you (and future maintainers), not the compiler.

Answer 5

I usually leave private out but I find it useful for lining up code:

private   int    x;
public    string y;
protected float  z;

VS:

int x;

public    string y;
protected float  z;

Answer 6

For completenes. And some people actually prefer to be explicit in their code about the access modifiers on their methods.