Do they yield the same result or different?

[Knightrider29]

Do they yield the same result or different?

1.

  bool tf; int n;
  if(1) tf = true, n=2; //plz explain this.. tf=true, 

2.

bool tf; int n;
  if(1) {tf = true; n=2;}

[LB]

They are the same, but you should prefer the second.

You may want to look up the boolean datatype.

[Knightrider29]

How can a comma(,) be used after tf=true

[LB]

The comma operator is a special operator in C++ that evaluates all arguments in order and returns the last.

http://ideone.com/Dl5Djs

In general it is a bad idea to use it.