Why is PHP printing my number in scientific notation, when I specified it as .000021?

Question

In PHP I have the following code:

<?PHP
  $var = .000021;
  echo $var;
?>

the output is 2.1E-5 !

Why? it should print .000021

Answer 1

2.1E-5 is the same number as 0.000021. That's how it prints numbers below 0.001. Use printf() if you want it in a particular format.

Edit If you're not familiar with the 2.1E-5 syntax, you should know it is shorthand for 2.1×10^-5. It is how most programming languages represent numbers in scientific notation.

Answer 2

Use number_format() to get what you're after:

print number_format($var, 5);

Also check sprintf()

Answer 3

Use number_format or sprintf if you want to see the number as you expect.

echo sprintf('%f', $var);
echo number_format($var, 6);

Answer 4

In general, a number is a number, not a string, and this means that any programming language treats a number as a number. Thus, the number by itself doesn't imply any specific format (like using .000021 instead of 2.1e-5). This is nothing different to displaying a number with leading zeros (like 0.000021) or aligning lists of numbers. This is a general issue you'll find in any programming language: if you want a specific format you need to specify it, using the format functions of your programming language.

Unless you specify the number as string and convert it to a real number when needed, of course. Some languages can do this implicitly.