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

# srand

## Synopsis

```perl
srand(42);             # deterministic sequence
srand;                 # seed from system entropy
my $seed = srand;      # returns the seed used
```

## Description

Seeds the pseudo-random number generator used by `rand`.

Sets the seed for the random number generator used by `rand`. If EXPR
is provided and defined, its integer value is used. Otherwise, a
system-derived seed (nanosecond timestamp XOR PID) is used. Creates a
new `StdRng` instance via `seed_from_u64`. Returns the seed that was
actually used as an integer.

## See also

rand