Beware that negative zero does not compare equal to positive zero.(PHP 4, PHP 5, PHP 7, PHP 8)
bccomp — Compare two arbitrary precision numbers
   Compares num1 to num2
   and returns the result of the comparison as an integer.
  
num1The left operand, as a string.
num2The right operand, as a string.
scalenull, it will default to the default scale set with bcscale(),
       or fallback to the value of the
       bcmath.scale INI directive.
      
     
   Returns 0 if both operands are equal,
   1 if num1 is greater than
   num2, -1 otherwise.
  
This function throws a ValueError in the following cases:
num1 or num2
     is not a well-formed BCMath numeric string.
    scale is outside the valid range.
    | Версія | Опис | 
|---|---|
| 8.0.0 | scaleis now nullable. | 
Приклад #1 bccomp() example
<?php
echo bccomp('1', '2') . "\n";   // -1
echo bccomp('1.00001', '1', 3); // 0
echo bccomp('1.00001', '1', 5); // 1
?>BEWARE! left and right operand is string!! so number in E-notation like 9.012E-6  need to be converted with sprintf('%F') to stringImprovement of functions bcmax() and bcmin() originaly written by frank at booksku dot com
<?php
function bcmax() {
  $args = func_get_args();
  if (count($args)==0) return false;
  $max = $args[0];
  foreach($args as $value) {
    if (bccomp($value, $max)==1) {
      $max = $value;
    }
  }
  return $max;
}
function bcmin() {
  $args = func_get_args();
  if (count($args)==0) return false;
  $min = $args[0];
  foreach($args as $value) {
    if (bccomp($min, $value)==1) {
      $min = $value;
    }
  }
  return $min;
}
?>If you want to compare 2 decimals for equality, bccomp does not works as expected:
bccomp("1.000000000000000","0.999999999999999",2)
returns 1
Instead, use
bcsub("1.000000000000000","0.999999999999999",2) == 0