Why does C# allow {} code blocks without a preceding statement?

Question

Why does C# allow code blocks without a preceding statement (e.g. if, else, for, while)?

void Main()
{
           


        

Answer 1

// if (a == b)
// if (a != b)
{
    // do something
}

Answer 2

Because C++ (and java) allowed code blocks without a preceding statement.

C++ allowed them because C did.

You could say it all comes down to the fact that USA programme language (C based) design won rather than European programme language (Modula-2 based) design.

(Control statements act on a single statement, statements can be groups to create new statements)

Answer 3

The general rule in C-syntax languages is "anything between { } should be treated as a single statement, and it can go wherever a single statement could":

• After an if.
• After a for, while or do.
• Anywhere in code.

For all intents and purposes, it's as the language grammar included this:

     <statement> :== <definition of valid statement> | "{" <statement-list> "}"
<statement-list> :== <statement> | <statement-list> <statement>

That is, "a statement can be composed of (various things) or of an opening brace, followed by a statement list (which may include one or more statements), followed by a closed brace". I.E. "a { } block can replace any statement, anywhere". Including in the middle of code.

Not allowing a { } block anywhere a single statement can go would actually have made the language definition more complex.

Answer 4

1Because...Its Maintain the Scope Area of the statement.. or Function, This is really useful for mane the large code..

{
    {
        // Here this 'i' is we can use for this scope only and out side of this scope we can't get this 'i' variable.

        int i = 0;
    }

    {
        int i = 0;
    }
}

Answer 5

It is not so much a feature of C# than it is a logical side-effect of many C syntax languages that use braces to define scope.

In your example the braces have no effect at all, but in the following code they define the scope, and therefore the visibility, of a variable:

This is allowed as i falls out of scope in the first block and is defined again in the next:

{
    {
        int i = 0;
    }

    {
        int i = 0;
    }
}

This is not allowed as i has fallen out of scope and is no longer visible in the outer scope:

{
    {
        int i = 0;
    }

    i = 1;
}

And so on and so on.

Answer 6

In the context you give, there is no significance. Writing a constant string to the console is going to work the same way anywhere in program flow.¹

Instead, you typically use them to restrict the scope of some local variables. This is further elaborated here and here. Look at João Angelo’s answer and Chris Wallis’s answer for brief examples. I believe the same applies to some other languages with C-style syntax as well, not that they’d be relevant to this question though.

---

¹ _{Unless, of course, you decide to try to be funny and create your own Console class, with a Write() method that does something entirely unexpected.}