Is “else if” faster than “switch() case”? [duplicate]

Answer 1

Believing this performance evaluation, the switch case is faster.

This is the conclusion:

The results show that the switch statement is faster to execute than the if-else-if ladder. This is due to the compiler's ability to optimise the switch statement. In the case of the if-else-if ladder, the code must process each if statement in the order determined by the programmer. However, because each case within a switch statement does not rely on earlier cases, the compiler is able to re-order the testing in such a way as to provide the fastest execution.

Answer 2

switch usually gets translated into a lookup table by the compiler, if possible. So lookup of an arbitrary case is O(1), instead of actually doing a few case comparisons before finding the one you want.

So in many cases an if/else if chain will be slower. Depending on the frequency with which your cases are being hit that may make no difference, though.

Answer 3

Short answer: Switch statement is quicker

The if statement you need two comparisons (when running your example code) on average to get to the correct clause.

The switch statement the average number of comparisons will be one regardless of how many different cases you have. The compiler/VM will have made a "lookup table" of possible options at compile time.

Can virtual machines optimize the if statement in a similar way if you run this code often?

Answer 4

Another thing to consider: is this really the bottleneck of your application? There are extremely rare cases when optimization of this sort is really required. Most of the time you can get way better speedups by rethinking your algorithms and data structures.

Answer 5

I'm not sure, but i believe the speed of one or the other changes depending on the programming language you're using.

I usually prefer to use switch. That way the code is simplear to read.

Answer 6

Switch is generally faster than a long list of ifs because the compiler can generate a jump table. The longer the list, the better a switch statement is over a series of if statements.