Generating a new variable on non-missing condition

[Zain Mian]

Hi

I have a small query. I am trying to generate a new variable (X), based on my existing 3 variables (A, B and C). I want the new variable X to equal A if A has a non-missing value. In case of A's value is missing, then X should equal B, if however if B's value is missing then X should equal C's value. I tried using if and else if commands but I am not being able to execute it properly. Kindly share any help or suggestions. Thank You.

[Jorrit Gosens]

No need for if/else:

gen x = a
replace x = b if a==.
replace x = c if b==.

[Nick Cox]

gen x = cond(a < ., a, cond(b < ., b, c))

is another way to do it. You're free to regard that as too confusing.