Which is the fastest way to get the absolute value of a number?

Question

How fast is an `if` (and why please). My college programing professors always told me to avoid `if`s for they are extremely slow, but I always forgot to ask how slow and why.

Answer 1

I disagree with the belief that if statements are slow and inefficient.

How else can one program anything involving selection without if statements?

If you are programming in a C based language (C/C++/java etc)

there is an alternative selection statement

// finds the absolute value of X

absVal = ( X >= 0) ? X : -X;

which the compiler expands to:

if (X>=0)

{

absVal = X;

}

else

{

ansVal = -X;

}

The only other way would be to tweak the sign bit, assuming

the programming language you are using allows that