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# The fibonacci.pl.c Polyglot
> Written by Paul Buetow 2014-03-24
In computing, a polyglot is a computer program or script written in a valid form of multiple programming languages, which performs the same operations or output independent of the programming language used to compile or interpret it
[https://en.wikipedia.org/wiki/Polyglot_(computing)](https://en.wikipedia.org/wiki/Polyglot_(computing))
## The Fibonacci numbers
For fun, I programmed my own Polyglot, which is both, valid Perl and C code. The interesting part about C is, that $ is a valid character to start variable names with:
```
#include <stdio.h>
#define $arg function_argument
#define my int
#define sub int
#define BEGIN int main(void)
my $arg;
sub hello() {
printf("Hello, welcome to Perl-C!\n");
printf("This program is both, valid C and Perl code!\n");
printf("It calculates all fibonacci numbers from 0 to 9!\n\n");
return 0;
}
sub fibonacci() {
my $n = $arg;
if ($n < 2) {
return $n;
}
$arg = $n - 1;
my $fib1 = fibonacci();
$arg = $n - 2;
my $fib2 = fibonacci();
return $fib1 + $fib2;
}
BEGIN {
hello();
my $i = 0;
for ($i = 0; $i <= 10; ++$i) {
$arg = $i;
printf("fib(%d) = %d\n", $i, fibonacci());
}
return 0;
}
```
You can find the whole source code at GitHub:
[https://github.com/snonux/perl-c-fibonacci](https://github.com/snonux/perl-c-fibonacci)
### Let's run it with Perl:
```
❯ perl fibonacci.pl.c
Hello, welcome to Perl-C!
This program is both, valid C and Perl code!
It calculates all fibonacci numbers from 0 to 9!
fib(0) = 0
fib(1) = 1
fib(2) = 1
fib(3) = 2
fib(4) = 3
fib(5) = 5
fib(6) = 8
fib(7) = 13
fib(8) = 21
fib(9) = 34
fib(10) = 55
```
### Let's compile it as C and run the binary:
```
❯ gcc fibonacci.pl.c -o fibonacci
❯ ./fibonacci
Hello, welcome to Perl-C!
This program is both, valid C and Perl code!
It calculates all fibonacci numbers from 0 to 9!
fib(0) = 0
fib(1) = 1
fib(2) = 1
fib(3) = 2
fib(4) = 3
fib(5) = 5
fib(6) = 8
fib(7) = 13
fib(8) = 21
fib(9) = 34
fib(10) = 55
```
It's really fun to play with :-).
E-Mail me your thoughts at comments@mx.buetow.org!
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