---
name: pack
status: documented
runtime: pp
source: src/runtime/pp/strings/pack.rs
---
```{index} single: pack; Perl built-in (pp runtime)
```

# pack

## Synopsis

```perl
my $bin = pack("A10", "hello");         # space-padded string
my $bin = pack("NnA*", $long, $short, $str);
my $bin = pack("(A2)*", @pairs);        # group repeat
```

## Description

Converts a list of values into a binary string according to a template.

Takes a TEMPLATE string and a LIST of values and packs them into a
binary string. The template is a sequence of format characters, each
optionally followed by a repeat count or `*` (consume all remaining).

Common format characters:

- `a`, `A`, `Z` -- ASCII string (null-padded, space-padded, null-terminated)
- `c`, `C` -- signed/unsigned char (8-bit)
- `s`, `S` -- signed/unsigned short (16-bit native)
- `l`, `L` -- signed/unsigned long (32-bit native)
- `q`, `Q` -- signed/unsigned quad (64-bit native)
- `n`, `N` -- unsigned short/long in network (big-endian) byte order
- `v`, `V` -- unsigned short/long in VAX (little-endian) byte order
- `f`, `d` -- single/double-precision float (native)
- `H`, `h` -- hex string (high/low nybble first)
- `w` -- BER compressed integer
- `U` -- Unicode code point
- `x` -- null byte padding
- `X` -- back up one byte
- `@` -- null-pad to absolute position
- `(...)N` -- group with repeat count

Whitespace and `#`-comments in templates are ignored.

## See also

unpack, vec