what should be the time gap between two babies?

i think we should leave atleast three years after having first child

Mahima.  As your friend very much like to have a female kid,yes! he can.
 
The gap between two child is after the of  the delivery of the first , a human should leave a space at least one year.  then it  would be quite comfortable. As you said, your friend has a four year male kid.  now he can.. ask him to wait for nothing... obvioulsy he can.. 

s two yrs is enough ....... we should give much gap between the two ....

i agree with honey...two years enough..

i'm a mother of 4,so i guess for me 3 years is the best gap in every child...

I think the next child should come when the first one is grown enough to accept the presence of the new baby and not needing too much attention from the mother.

I dont think that there is a right answer to this.  I have 4 children.  My first two are 3 yrs apart.  I really liked that span, so I was going to have my third child 3 yrs after my second. That didn't end up happening, they are only 2 yrs apart.  I liked that span too, so I tried to have my fourth child 2 yrs after my third child. That didn't happen either~ she came 6 yrs later.  That is a huge span, but now that the boys are older, I still have my daughter to hang out with.

As for me, I don't think there should really be a right span. Whatever your choice would do. As long as you raise the kids okay, then everything's going to be fine.

 Everyone is a little different but for me, if I did it over again I would not have waited so long. I had my first with someone I thought I would spend the rest of my life with, that did not turn ot to be the case - we are now (happily) seperated and I have been with my spouse (my best friend) for quite sometime. The difference between both of my babies is almost 5 years even and that was too long for me. 

I think a minimum of two years is good.  Personally, I would want to get the first one potty-trained before I had the second one. Diapers are expensive!

For me, it was eighteen months. I have two girls and they get along just perfectly. Since they are pretty close in age, they play together very often and my older one loves to teach her little sister new things or help with her homework. I think it is best not to wait too long, because that might create a gap in siblings' understanding and relating to each other.

Joyjoy made a great point!  You really should get the first one potty trained before having another baby. If you don't, the first child will want to stay in diapers because the new baby has diapers and is getting most of the attention.   I'd wait until the first child is about 3 so they can be a helper with the new baby.  When new babies arrive the older siblings tend to get jealous unless they are involved.

I do believe Antkmom awas right when she said there is no right or wrong answer. I have 3 children and there is 12 years difference between the oldest and youngest. They get along great. My sister has 3 children and they are 2 years apart. They also get along great. It just depends on the child.