"if" or "else if"

[steveinaustria]

I am new to C and In the loop part of an Arduino sketch if I make a list of "if" statements the script compiles, runs and works. But I have a feeling that after the first if statement the following ones should be "else if" statements. Is the second method more efficient? and could there be problems just using "if" statements.

[wildbill]

It depends, both versions have their place. Post the code you're worried about.

[jimLee]

A list of ifs is kinda' like "here try all of these, do the ones that are true." A block of if-else ifs is kinda like "Try these, only do the first one that is true. Skip the rest."

-jim lee

[missdrew]

Perhaps:
A = 0

loop
if a == 0 do stuff : a++
if a == 1 do stuff : a++

would do the first, then the second action

A = 0

loop
if a == 0 do stuff : a++
elseif a == 1 do stuff : a++

would do the first, then NEXT TIME through the loop, it would do the second.

[johnwasser]

There is a shortcut for a stack of 'if-else-if' where all are testing the same integer value against a bunch of constants:

int VAR;
  if (VAR == 3)
  {
     // Do stuff for 3
  }
  else if (VAR == 17)
  {
     // Do stuff for 17
  }
  else if (VAR == 5)
  {
     // Do stuff for 5
  }
  else
  {
    // Do stuff for no match
  }

The shortcut is the 'switch/case' statement:

int VAR;
  switch (VAR)
  {
  case 3:
     // Do stuff for 3
     break;

  case 17;
     // Do stuff for 17
     break;

  case 5:
     // Do stuff for 5
     break;

  default:
    // Do stuff for no match
    break;
  }