You can think of Perl scalars as just being strings. Using any of these strings in a place that wants a numeric value will cause the string to (try to) be interpretted as a decimal numeral. There are some details beyond this that almost never matter.

pack creates a "raw" string of bytes from multiple input values. unpack creates multiple output values from a "raw" string of bytes.

The documentation for pack and unpack are terse enough that I usually have to resort to experimentation to flush out the details even though I am very familiar with them already. "perl -de 0" and its "x" command are very useful for this.

So most of the pack formats take a string holding the decimal representation of a number, and encode that number into the "raw" format mentioned in the description of that format character, returning the "packed" string that holds the bytes of that "raw-formatted" data concatenated together.

The exceptions are the formats that mention "string" in their description along with "x", "X", and "@".

So: 

> perl -de 0
[...]
  DB<1> x pack("C","65")
0  'A'
  DB<2> x unpack("C*","\0\cA A") # yields ("0","1","32","65")
0  0
1  1
2  32
3  65
  DB<3> x pack("n","1")
0  "\c@\cA"

[download]
where I've put quotes around many of the "numbers" even though they aren't required just to emphasize that Perl, to a great extent, simply treats them as strings that happen to contain valid decimal representations for numbers.

        - tye (but my friends call me "Tye")

In reply to (tye)Re: Determine type of variable by tye
in thread Determine type of variable by Jrax

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