PHP Comparison for one less than

Question

Google really let me down for this one. I want to do a comparison for less than or greater than but only by 1. So I can detect if say value B is one less than or one greater than A.

if (A is one less than B || A is one greater than B) {
 return true
}

That's what I want to do.

Answer 1

If you always want to check if its one above or one below, differentiate the two, and see if the absolute value of the result is one.

if (abs($a - $b) === 1) {
    // Do your thing
}

See this live demo .

Answer 2

Do a standard equality test.

Just perform the subtraction or addition on the value you're comparing to.

3 === (4-1)

Answer 3

Something like this. As long as the different between $a and $b is 1 .

if(abs($a - $n) == 1) {...}

Answer 4

Translating your pseudo condition:

(A is one less than B) or (A is one greater than B)

this becomes:

if ( $A === $B-1 || $A === $B+1 ) {
  return true;
}