![]() ![]() ![]() Sub ( Int:D $i is copy where * >= 0 -> Str:D ) ).reverse.join( '|' ). I’ll collect the string values then join them: From that I get the base that I’ll use to decompose the number and I’ll break up the string into characters in an array so I can use the numeric value as the index to map it onto its string value. If I don’t specify a string I’ll default to the decimal digits. ![]() Specify a stupid string and get stupid number serializations. Maybe they aren’t in order of their codepoints, or they are repeated, or some other weird thing. I don’t care which characters are in the string. I create a factory that takes a single string where each character represents a digit the number of digits is the base. Optimizing that lookup table is most of the problem but I don’t worry about that right away. Put together all your string parts to get the full number. The solution is to decompose a number into parts and convert that partto a string with a lookup table. How about a converter for arbitrary bases with arbitrary digits? And, I can’t use any of the builtin stuff to make this work (and so far I haven’t peeked to see how Rakudo does it). There are probably some hexadecimal converters out there. The solutions I found convert everything to decimal numbers. Since this is also a typical interview problem I thought I’d work on it in Perl 6 with a few extras. Much of his discussion is special to C or C++ where you (think) you directly control the hardware. If you’ve bought into the JSON mania you’re probably serializing numbers as strings quite a bit without even thinking about it. Paul Khuong wrote about this in How to Print Integers Really Fast (With Open Source AppNexus Code!). My $f2 = $n->round('','-2','zero') # returns 123.Turning numbers into strings can be a big waste of time and money. The Math::BigFloat extension also supports various rounding modes: use Math::BigFloat The str() function converts values to a string form so they can be combined with. The Math::Round extension provides various functions for rounding floating-point values: use Math::Round qw(:all) The Python style (unlike Perl) is to halt if it cant tell what to do. You want to convert a string (e.g., 0b10110, 0x55, or 0755) containing a binary, octal, or hexadecimal number to the correct number. The variable $# contains the default format for printing numbers, but its use is considered deprecated. Unfortunately, they're also two of the most misunderstood and most often overlooked functions that Perl provides. Note that this implicitly uses round-to-even. pack and unpack are two functions for transforming data according to a user-defined template, between the guarded way Perl stores values and some well-defined representation as might be required in the environment of a Perl program. To format output: printf("%.2f", 1.2) # prints 1.20 9 Answers Sorted by: 96 You don't need to convert it at all: perl -e 'print '5.45' + 0.1 ' 5. Math::BigInt and Math::BigFloat extensions, but it does not seem to support fraction literals. The Math::BigRat extension provides similar functionality. ![]() The Number::Fraction extension provides a fraction type that overloads the arithmetic operators with symbolic fraction arithmetic: use Number::Fraction ':constants' Hex to String converters can be used for a variety of purposes, such as converting data values into a human-readable format or converting code values into a. The Math::BigFloat extension provides an arbitrary-precision decimal type: use Math::BigFloat ':constant' Perl can also store decimal numbers as strings, but the builtin arithmetic operators will convert them to integer or floating-point values to perform the operation. Perl supports platform-native floating-point as scalar values in practice this usually means IEEE 754 double precision. Floating-point cheat sheet for Perl Floating-Point Types ![]()
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