Commenting out the Comment ?

#codenewbie

Disclaimer: This is not essentially a productivity tip. But rather, something I experienced while coding.

The Context

I was casually sharing some programming differences to my friends. The programming language was C, the topic was:

Difference between if-else if and if if conditions.
And the code was like:

void main(){

    // if-if statement

    if(2+2 == 4){
       printf("\nI execute because 2+2 is 4.");
    }
    if(5+3 == 8){
       printf("\nI execute because 5+3 is 8.");
    }

    // if-else if statement

    if(9+8 == 17){
       printf("\nI execute because 9+8 is 17.");
    }else if(9+3 = 12){
       printf("\nI execute because 9+3 is 12.")
    }
}

At first, I wanted to demonstrate the if-if statement. Therefore I commented the if-else if statement out.

void main(){

    // if-if statement

    if(2+2 == 4){
       printf("\nI execute because 2+2 is 4.");
    }
    if(5+3 == 8){
       printf("\nI execute because 5+3 is 8.");
    }

    // if-else if statement

    /*
    if(9+8 == 17){
       printf("\nI execute because 9+8 is 17.");
    }else if(9+3 = 12){
       printf("\nI execute because 9+3 is 12.")
    }
    */
}

After the first demonstration, I had to demonstrate the if-else if statement. So, in order to make it executable, obviously I had to uncomment it by removing those /* */ symbols (aka multiple line comment).

But, I being Rahul Dahal, had a crazy thought like,

"What if I put // (aka single line comment) before the /* & */ (multiple line comment start and end), to comment them out and make the text inside it executable ?"

Basically, I wanted to check if we can comment out a comment. So that comment will no longer be a comment.

I did that.

void main(){

    // if-if statement

    if(2+2 == 4){
       printf("\nI execute because 2+2 is 4.");
    }
    if(5+3 == 8){
       printf("\nI execute because 5+3 is 8.");
    }

    // if-else if statement

    // /*
    if(9+8 == 17){
       printf("\nI execute because 9+8 is 17.");
    }else if(9+3 = 12){
       printf("\nI execute because 9+3 is 12.")
    }
    // */
}

And guess what, it worked!

That trick worked. As I expected.

But Why? Why did it work ?

Answer,
Actually what happens is, whatever we type after the comment starter (both // & /*), no matter what, the compiler understands it as a comment text.

That is why the /* itself was treated as a normal text.

And since, /* is treated as a normal text, the code after it will no longer be commented out. Hence, making it executable.