It's kind of a common knowledge that (most of) floating point numbers are not stored precisely (when IEEE-754 format is used). So one shouldn't do this:

0.3 - 0.2 === 0.1; // very wrong 

... as it will result in false, unless some specific arbitrary-precision type/class was used (BigDecimal in Java/Ruby, BCMath in PHP, Math::BigInt/Math::BigFloat in Perl, to name the few) instead.

Yet I wonder why when one tries to print the result of this expression 0.3 - 0.2, scripting languages (Perl and PHP) give 0.1, but "virtual-machine" ones (Java, JavaScript and Erlang) give something more similar to 0.09999999999999998 instead?

And why it's inconsistent with Ruby: version 1.8.6 (codepad) gives 0.1, version 1.9.3 (ideone) - 0.0999...?

It's kind of a common knowledge that (most) floating point numbers are not stored precisely (when IEEE-754 format is used). So one shouldn't do this:

0.3 - 0.2 === 0.1; // very wrong 

... as it will result in false, unless some specific arbitrary-precision type/class was used (BigDecimal in Java/Ruby, BCMath in PHP, Math::BigInt/Math::BigFloat in Perl, to name a few) instead.

Yet I wonder why when one tries to print the result of this expression, 0.3 - 0.2, scripting languages (Perl and PHP) give 0.1, but "virtual-machine" ones (Java, JavaScript and Erlang) give something more similar to 0.09999999999999998 instead?

And why is it also inconsistent in Ruby? version 1.8.6 (codepad) gives 0.1, version 1.9.3 (ideone) gives 0.0999...

It's kind of a common knowledge that (most of) floating point numbers are not stored precisely (when IEEE-754 format is used). So one shouldn't do this:

0.3 - 0.2 === 0.1; // very wrong 

... as it will result in false, unless some specific arbitrary-precision type/class was used (BigDecimal in Java/Ruby, BCMath in PHP, Math::BigInt/Math::BigFloat in Perl, to name the few) instead.

Yet I wonder why when one tries to print the result of this expression 0.3 - 0.2, scripting languages (Perl and PHP) give 0.1, but "virtual-machine" ones (Java, JavaScript and Erlang) give something more similar to 0.09999999999999998 instead?

And why it's inconsistent with Ruby: codepad version gives 0.1, ideone's one - 0.0999...?

It's kind of a common knowledge that (most of) floating point numbers are not stored precisely (when IEEE-754 format is used). So one shouldn't do this:

0.3 - 0.2 === 0.1; // very wrong 

... as it will result in false, unless some specific arbitrary-precision type/class was used (BigDecimal in Java/Ruby, BCMath in PHP, Math::BigInt/Math::BigFloat in Perl, to name the few) instead.

Yet I wonder why when one tries to print the result of this expression 0.3 - 0.2, scripting languages (Perl and PHP) give 0.1, but "virtual-machine" ones (Java, JavaScript and Erlang) give something more similar to 0.09999999999999998 instead?

And why it's inconsistent with Ruby: version 1.8.6 (codepad) gives 0.1, version 1.9.3 (ideone) - 0.0999...?