CODEWITHSUNDEEP
php
Sarotobi
Sarotobi

Reputation: 831

PHP how to use range() for float numbers

Is there a way to use PHP range() for a really small number? like below?

range(0.54,0.58);

Doing this creates an error.

range(): step exceeds the specified range in

Upvotes: 8

Views: 2905

Answers (5)

Den
Den

Reputation: 614

The other answers here did not work for me as, due to rounding error with floats, the result is not exact:

  • Depending on the start and end numbers the result is inclusive or exclusive the end number.
  • Additionally in PHP 8 the rounding errors are visible in the result. (Seams to only apply to debug output.)

Examples:

php 7.4: (inclusive vs. exclusive)

php > var_dump(range(0.54, 0.6, 0.01));  
array(6) {
  [0]=>
  float(0.54)
  [1]=>
  float(0.55)
  [2]=>
  float(0.56)
  [3]=>
  float(0.57)
  [4]=>
  float(0.58)
  [5]=>
  float(0.59)
}
php > var_dump(range(0.52, 0.6, 0.01)); 
array(9) {
  [0]=>
  float(0.52)
  [1]=>
  float(0.53)
  [2]=>
  float(0.54)
  [3]=>
  float(0.55)
  [4]=>
  float(0.56)
  [5]=>
  float(0.57)
  [6]=>
  float(0.58)
  [7]=>
  float(0.59)
  [8]=>
  float(0.6)
}

php 8.0: (inclusive vs. exclusive + rounding errors)

php > var_dump(range(0.54, 0.6, 0.01));
array(6) {
  [0]=>
  float(0.54)
  [1]=>
  float(0.55)
  [2]=>
  float(0.56)
  [3]=>
  float(0.5700000000000001)
  [4]=>
  float(0.5800000000000001)
  [5]=>
  float(0.5900000000000001)
}
php > var_dump(range(0.52, 0.6, 0.01));
array(9) {
  [0]=>
  float(0.52)
  [1]=>
  float(0.53)
  [2]=>
  float(0.54)
  [3]=>
  float(0.55)
  [4]=>
  float(0.56)
  [5]=>
  float(0.5700000000000001)
  [6]=>
  float(0.5800000000000001)
  [7]=>
  float(0.5900000000000001)
  [8]=>
  float(0.6)
}

Solution:

This does give my expected result (PHP 7.4 and up):

php > var_dump(array_map(fn($n) => $n/100, range(0.54*100, 0.6*100,  0.01*100)));
array(7) {
  [0]=>
  float(0.54)
  [1]=>
  float(0.55)
  [2]=>
  float(0.56)
  [3]=>
  float(0.57)
  [4]=>
  float(0.58)
  [5]=>
  float(0.59)
  [6]=>
  float(0.6)
}

Upvotes: 0

Jon
Jon

Reputation: 2128

use the third parameter to set a step

range(0.54,0.58, 0.01);

or you could multiply your values by 1000 and then divide by 1000 which would be silly...

Upvotes: 1

axiac
axiac

Reputation: 72266

The error message is self-explanatory: the default value of $range (the third argument of range()) is 1 and using it produces an empty range.

Provide a third argument to range(). From the value of $start and $end I think 0.01 is the step you need:

range(0.54, 0.58, 0.01)

Check it out: https://3v4l.org/IcUAh

Upvotes: 3

Dimitris Filippou
Dimitris Filippou

Reputation: 809

You should also provide the range you want.

Like this

var_dump(range(0.54,0.58,0.01));

output is

array(4) {
  [0]=>
  float(0.54)
  [1]=>
  float(0.55)
  [2]=>
  float(0.56)
  [3]=>
  float(0.57)
}

Upvotes: 3

BritishWerewolf
BritishWerewolf

Reputation: 3968

The third parameter is the step.
Reading the documentation is a very good place to start.

If you read you will see that you can set the step to something that can increment between your limits.
The error message is simply telling you that it cannot increment 0.54 by 1 without going over 0.58 - think about, it 1 + 0.54 is more than 0.58!

Using this line instead will give you the desired output.

range(0.54, 0.58, 0.01);

Upvotes: 8

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