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### Read file text and find fibonacci series

by darkblackblue (Novice)
 on Dec 28, 2017 at 14:37 UTC Need Help??

Hi My goal is read only line from file , and find fibonacci series that has minimun 3 element.I want to control numbers from 1 to 6 digit. Fibonacci series starts 1,1,2,3,5,8,13,21,34,55,89, ...... .For example;File text document

49693463452312343388645

I division string 1 to 6 digit. Check 4 is fibonacci number , no , go ahaed 49 is fibonacci number , no, next 496 is fibonacci ,no, 4969 after 44693 ,after 496934 no.There isnt any fibonacci , go to next digit and do it again 9 , 96,969,9693,96934.

```use 5.010;
use strict;
use warnings;
open(FILE, "<:encoding(UTF-8)", "aa.txt") or die "Could not open file:
+ \$!";
my \$numbers;
while (<FILE>) {
\$numbers="\$_" ;
print "\$_";
}
chomp \$numbers;
print "\n\$numbers";
my \$len=length(\$numbers);
print "\n\$len\n";
my \$i;
my \$abc;
foreach my \$i (0..\$len){
foreach my \$j (1..6) {
print "\$j----->";
\$abc = substr(\$numbers,\$i,\$j);
print "\$abc\n";
}
print "***********************************\n";
}
close FILE;

I read to find fibonacci series with PERFECT SQUARE. I didn't use it. C code example

```// C++ program to check if x is a perfect square

#include <iostream>
#include <math.h>
using namespace std;

// A utility function that returns true if x is perfect square
bool isPerfectSquare(int x) {
int s = sqrt(x);
return (s*s == x);
}

// Returns true if n is a Fibinacci Number, else false
bool isFibonacci(int n) {
// n is Fibinacci if one of 5*n*n + 4 or 5*n*n - 4 or both
// is a perferct square
return isPerfectSquare(5*n*n + 4) || isPerfectSquare(5*n*n - 4);
}

// A utility function to test above functions
int main() {
for (int i = 1; i <= 10; i++)
isFibonacci(i)? cout << i << " is a Fibonacci Number \n":
cout << i << " is a not Fibonacci Number \n" ;
+
return 0;
}

2017-12-29 Athanasius restored original content

Replies are listed 'Best First'.
Re: Read file text and find fibonacci series
by haukex (Chancellor) on Dec 28, 2017 at 19:12 UTC

This appears to have been posted to Meditations, but I'm not sure if you meant it to be a question? Anyway, you're describing scanning a string looking for a pattern, which is exactly what regular expressions are good at. Ignoring the duplicate 1's, there are only 29 Fibonacci numbers with 1 to 6 digits, a regex can handle that just fine (and it would have no problem handling much more). See Building Regex Alternations Dynamically.

This code can handle huge numbers too, try changing \$DIGITS to e.g. 60. And note that you can use the same regex to find sequences of numbers, e.g. (?:\$re){3,} (although that doesn't check if they are consecutive in the sequence).

```#!/usr/bin/env perl
use warnings;
use strict;

my \$DIGITS = 6;

my %fib;
{ use bigint;
for ( my (\$f,\$t)=(1,1); length(\$f)<=\$DIGITS; (\$f,\$t)=(\$t,\$f+\$t) ) {
my \$s = "\$f";
\$fib{\$s} = [\$s];
while (length \$s > 1) {
chop \$s;
push @{\$fib{\$f}}, \$s if exists \$fib{\$s};
}
} }
#use Data::Dump; dd \%fib;
print "There are ",0+keys(%fib)," fibs with up to \$DIGITS digits\n";

my (\$re) = map {qr/\$_/} join '|', map {quotemeta}
sort { length \$b <=> length \$a or \$b cmp \$a } keys %fib;
print "\$re\n";

while (<DATA>) {
chomp;
print "Searching '\$_'\n";
while (/(?=(\$re))./g) {
print "Found ",join(', ',@{\$fib{\$1}})," at ",\$-[0],"\n";
}
}

__DATA__
496934634523123433886451447233402467622113
690168906931029935139391829792095612517948949963798093315456

Update: You appear to have edited your node to remove its content, please see How do I change/delete my post? for why you shouldn't do that. Content restored, thanks Athanasius. Also made very minor fixups.

Hi, haukex.

while (/(?=(\$re))./g) { ... }

"Look for a fib anywhere ahead, then if found, consume its leftmost digit, then repeat" probably makes no sense, even for this assignment/homework. The %fib was built but not actually used. The "3 element" part of assignment (not addressed in your code) could be either consecutive, or just ascending fibs. But, the way %fib was constructed, it may be to help looking for a fib whose initial digits are a fib too, whose initial digits, ..., etc. While leftmost digit of any 2-digit fib is a fib, -- I wonder if any value of %fib could be an array with more than 3 elements? :)

P.S. Please, I'm not appealing to rewrite anything, don't waste your time, the task is too much unclear.

P.P.S. And, I suspect the "PERFECT SQUARE" in OP, in C, won't work for 6-digit numbers and int type, because of overflow?

The %fib was built but not actually used.

Well not quite, it is used for what you said:

to help looking for a fib whose initial digits are a fib too

This is what I was using it for, since I didn't feel like getting too fancy with the regex. The code I wrote was mostly just an implementation of my interpretation of the description the OP gave:

"Check 4 is fibonacci number , no , go ahaed 49 is fibonacci number , no, next 496 is fibonacci ,no, 4969 after 44693 [sic] ,after 496934 no.There isnt any fibonacci , go to next digit and do it again 9 , 96,969,9693,96934."
I wonder if any value of %fib could be an array with more than 3 elements?

Good question, I didn't try cranking up \$DIGITS past 60 yet...

the task is too much unclear

Agreed, which is why I just implemented the part I (thought I) understood ;-)

Re: Read file text and find fibonacci series
by thanos1983 (Parson) on Jan 02, 2018 at 18:00 UTC

Hello darkblackblue,

As the fellow Monks say this looks like a school assignment. Well I could suggest another approach to your problem but it only contains half of the solution, I have left the rest for you to solve.

Sample of code:

I used different hard coded input instead of reading your data from your file but you get the point that the input is data from your file. What I am doing on this sample of code is comparing the string part by part as you wanted with a list of fibonacci numbers. The module that I am using is Math::Fibonacci. What the script does not do is to compare the numbers by subtracting the elements one by one until the end as you described. I have left this part out.

Update: I just observed that the darkblackblue has asked the question since the 28th December. I assume that he/she was not able to resolve it. Just to add complete answer to the question for future reference see sample of code bellow:

Hope this helps, BR.

Seeking for Perl wisdom...on the process of learning...not there...yet!
Re: Read file text and find fibonacci series
by aartist (Monk) on Jan 02, 2018 at 15:14 UTC
Is it a programming exercise or you are solving a mathematical problem?

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