Ternar operator

What's the works faster?
template <typename T> T abs(T n) {return n<0 ? n : n;}
or
template <typename T> T abs(T n) {return n*(n<0 ? 1 : 1);}

Before I answer, I'll tell you what. this information will help nothing.♪ Why?
 It's a template. It will be installed for each type separately, so the result depends heavily on type (code may not be computed with some types at all). You want to compare, tell me what type you're interested in. And I'll behave like C, and I'll assume.
int
♪ abs
There's a standard library, and there's reason to think it's as effective as possible. It's a microoptimization that you don't think you'll notice at all times. Let's just say, the time you're saving is likely to cost all the users in the entire life of your program even the time I wrote this answer.
:)
But let's https://gcc.godbolt.org/#%7B%22version%22%3A3%2C%22filterAsm%22%3A%7B%22labels%22%3Atrue%2C%22directives%22%3Atrue%2C%22commentOnly%22%3Atrue%7D%2C%22compilers%22%3A%5B%7B%22sourcez%22%3A%22C4TwDgpgJhBmAEBLAdseAVA3AKHfAhgEYDOAFHsgJTwDeAThMAK53LzIA8ADPAPzwBaNgC52mAL7ZcBEgCZy7avUYs2yAFSlOPfgICM8UXsoSgAA%22%2C%22compiler%22%3A%22g530%22%2C%22options%22%3A%22O3%22%7D%5D%7D c
int
:typedef int T; T abs(T n) {return n<0 ? n : n;}
T abs2(T n) {return n*(n<0 ? 1 : 1);}
Output at x86 GCC 5.3.0 with flag
O3
:abs(int):
movl %edi, %edx
movl %edi, %eax
sarl $31, %edx
xorl %edx, %eax
subl %edx, %eax
ret
abs2(int):
movl %edi, %eax
sarl $31, %eax
orl $1, %eax
imull %edi, %eax
ret
The code is different. As you can see, the second option is shorter. Does that mean he's faster? Not a fact. The result depends on implementation in the processor, but multiplication is technically more difficult to read, so it takes a little longer.
But that's all about it.
int
♪ You can check the other types you're interested in, just putting him in.typedef
The same instrument. But there's always one answer to "speed" questions. Measure!
 It's a template. It will be installed for each type separately, so the result depends heavily on type (code may not be computed with some types at all). You want to compare, tell me what type you're interested in. And I'll behave like C, and I'll assume.