```{index} single: is_strict; version function ``` ```{index} single: version::is_strict; Perl function ``` # is_strict Test whether a string is a strict version suitable for CPAN indexing. ## Synopsis ```perl version::is_strict($str); version->is_strict($str); ``` Strict versions rule out alpha underscores and unusual shapes. A decimal version must be a single dot between two digit runs; a dotted-integer version must start with `v` and have at least three components. This is the form PAUSE expects for permanent releases. ## What you get back A boolean: `1` if the string matches the strict grammar, the empty string otherwise. ## Examples ```perl version::is_strict("1.02"); # 1 version::is_strict("v1.2.3"); # 1 version::is_strict("1.2.3"); # "" — needs the v prefix version::is_strict("1.02_03"); # "" — underscores disallowed version::is_strict("v1.2"); # "" — needs 3+ components ``` ## Differences from upstream Fully compatible with upstream version {{ upstream.version }}. ## See also - `is_lax` — the permissive counterpart - `declare` — the recommended way to produce a strict dotted-integer