To “if, if, if” or to “if, else if, else if, else” [closed]

Answer 1

It depends on the language and the surrounding APIs

The first solution is an typical imperative approach, the focus is on the act of checking something: abort if a, abort if b, abort if c, success.

The second solution is a more functional aproach, one could read it as the curly brace in mathematical definitions (as in: fac(n) = { n <= 1: 1, n > 1: n * fac(n-1)).

The solution should be chosen to match the environment. In Java, Python, etc it would be the first. In ruby the second could be fine.

Answer 2

Both are identical. The compiler is likely to figure out how to optimize them so that identical machine code is emitted. I would prump for the 1st code as it is easier to read.

Answer 3

It mostly depends on how the compiler optimize the resulting code.

the if(.) is typically translated with a compare_to_zero instruction, followed by a conditional jump.

In your case, this will be

CMP(c1)
RETZ
CMP(c2)
RETZ
CMP(c3)
RETZ

or (with the else-s)

   CMP(c1)
   JNZ(a1)
   RET
a1:CMP(c2)
   JNZ(a2)
   RET
a2:CMP(c3)
   JNZ(a3)
   RET
a3:RET

A second pass of the optimizer will see the chain of jumps, invert the then/else (and Z/NZ) skip off the jumps, being at the point a "jump to next", giving exactly the previous code.

Answer 4

I would do this:

return SubTest1(sample) && SubTest2(sample) && SubTest3(sample);

This won't improve performance, but what the function do may (or may not) be more obvious.