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

# vec

## Synopsis

```perl
my $val = vec($string, $offset, $bits);
vec($string, $offset, $bits) = $value;
```

## Description

Treats a string as a bit vector and accesses individual bitfields.

Treats EXPR as a bit vector made up of elements of width BITS and
returns the unsigned integer value of the element at OFFSET.
BITS must be a power of 2 from 1 to 32.

As an lvalue, `vec` stores values into the specified bitfield,
growing the string as needed.

```perl
my $flags = "";
vec($flags, 0, 8) = 255;     # Set byte 0 to 255
vec($flags, 1, 8) = 10;      # Set byte 1 to 10
my $val = vec($flags, 0, 8); # Get byte 0 (255)
my $bit = vec($flags, 5, 1); # Get bit 5 of byte 0
```

## See also

pack, unpack