diff options
Diffstat (limited to 'pod/perlfunc.pod')
| -rw-r--r-- | pod/perlfunc.pod | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index dfacad5146..e0ca04f631 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -3188,7 +3188,11 @@ brackets, as in C<pack 'C[80]', @arr>. One can replace the numeric repeat count by a template enclosed in brackets; then the packed length of this template in bytes is used as a count. -For example, C<x[L]> skips a long (it skips the number of bytes in a long). +For example, C<x[L]> skips a long (it skips the number of bytes in a long); +the template C<$t X[$t] $t> unpack()s twice what $t unpacks. +If the template in brackets contains alignment commands (such as C<x![d]>), +its packed length is calculated as if the start of the template has the maximal +possible alignment. When used with C<Z>, C<*> results in the addition of a trailing null byte (so the packed result will be one longer than the byte C<length> @@ -3411,6 +3415,18 @@ character. =item * +C<x> and C<X> accept C<!> modifier. In this case they act as +alignment commands: they jump forward/back to the closest position +aligned at a multiple of C<count> bytes. For example, to pack() or +unpack() C's C<struct {char c; double d; char cc[2]}> one may need to +use the template C<C x![d] d C[2]>; this assumes that doubles must be +aligned on the double's size. + +For alignment commands C<count> of 0 is equivalent to C<count> of 1; +both result in no-ops. + +=item * + A comment in a TEMPLATE starts with C<#> and goes to the end of line. =item * |