![]() ![]() Var "representation" is the empty string. Scalar variable /usr/bin/perl Scalars hold just single data type: string, number or perl reference Scalars definition in Perl scalarnumber -5. I looked at using CRC32 but the resulting integer wasn't always the same each time. The catch is that the conversion must be deterministic (i.e. One of my needs is to convert a string into a 32-bit integer. Var "size" is the number of digits of the new representation. this function assumes that a character string is a number written in octal format and converts it into a decimal number. Converting string to unique integer in perl JI'm writing some perl code for a project I'm working on. Var "n" is the number we want to represent. I do consider it 'built-in' even when its just in core modules, so Im not criticizing Perl here for failing to pollute the global namespace. # the digits are sorted in ascending order. Even JavaScript, which, like Perl, has less need for explicit type-conversion to/from string/integer due to the weak-typing provides parseInt as a global function. # the size of digits is the base of our new representation Let "digits" be the array containing all the digits of our representation. The algorithm to convert a number to base-n is simple: # pseudocode My perl is built with 64-bit integers (see perl -v to check your support), so your number isn't "too large" for me. Your number 21767823360 needs about 35 bits. 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. ![]() This transparently enables infinite-precision arithmetics. Sub ( Int:D $i is copy where * >= 0 -> Str:D ) ).reverse.join( '|' ).Perl has little problems with big numbers, and if your numbers are really huge, just use bignum. 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. The int + 0.5 causes real issues with -negative numbers, unless you want it to work that way, but I imagine most people dont. 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. The numerical value is just the same thing. If the string looks like a number to perl, then it is easy. The string > number conversion might leave you thinking a bit. I create a factory that takes a single string where each character represents a digit the number of digits is the base. It is just a matter of imaging as if '' appeared around the number value. 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!). ![]() ![]() Turning numbers into strings can be a big waste of time and money. ![]()
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