trying to understand syntax - Xtreme .NET Talk

04-24-2011, 02:16 PM

jimmythefloyd jimmythefloyd is offline

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trying to understand syntax

How come I don't have to use a semicolon after the "i++" in the for loop, but if I were to write i++ after the console.writeline i would. Is it just just some kind quirky thing? or is there some deeper logic behind it.

Code:

    for (int i = 0; i < 12; i++ ) // doesn't need it, won't accept it here
            {
                Console.WriteLine(myClass.MethodA());
                i++;  // Would need semicolon here
            }
            
            Console.ReadLine();

04-25-2011, 04:06 PM

snarfblam

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Re: trying to understand syntax

Quote:

Originally Posted by jimmythefloyd

Is it just just some kind quirky thing?

The short answer is yes.

This syntax is inherited from C. It does seem inconsistent. However, consider the structure of the for statement (not sure if this is 100% technically correct, but it gets the idea across):

Code:

for (statement; expression; expression) 
    statement

Normally, a semi-colon denotes the end of a statement. As you can see, the last two are expressions. In this case, we are using the semi-colon as more of a delimiter. You don't normally write code with a trailing delimiter.

Code:

int x, y, z,;

At the same time, C# does accept trailing commas in some cases. One reason for this is because it makes code generation simpler. (I use trailing commas in enums and initializers if they are declared across multiple lines.)

Code:

int[] x = {0, 1, 2, 3, };
var x = new { A = "Aye", B = "Bee", };
enum x {a, b, c, }

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07-21-2011, 04:14 PM

cloudmonkey cloudmonkey is offline

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Re: trying to understand syntax

Quote:

Originally Posted by jimmythefloyd

Code:

    for (int i = 0; i < 12; i++ ) // doesn't need it, won't accept it here
            {
                Console.WriteLine(myClass.MethodA());
                i++;  // Would need semicolon here
            }
            
            Console.ReadLine();

The semi colon has always been used as a stopper at the end of a statement. A loop needs to be told to continue on, while a statement is the end of the line.