Languages
FsharpActionScript
xBase
Clean
GPSS
PureBasic
Sieve
Erlang
JOVIAL
Mercury
Linda
DataFlex
PostScript
FoxPro2
VFP
Cobol
Prolog
Jython
Awk
VisualBasic
JavaScript
Matlab
ASP
Haskell
Csharp
D
Smalltalk
Nemerle
Pixilang
Java
SQL
Python
ObjectPascal
Ruby
Perl
Pascal
Assembler
PHP
C
| Functions | Add function | Users Registration | Enter | About | ASCII Table | Our helpers |
each in Perl |
|
each HASH
When called in list context, returns a 2-element list consisting of the key and value for the next element of a hash, so that you can iterate over it. When called in scalar context, returns only the key for the next element in the hash. Entries are returned in an apparently random order. The actual random order is subject to change in future versions of perl, but it is guaranteed to be in the same order as either the keys or values function would produce on the same (unmodified) hash. Since Perl 5.8.1 the ordering is different even between different runs of Perl for security reasons (see "Algorithmic Complexity Attacks" in perlsec). When the hash is entirely read, a null array is returned in list context (which when assigned produces a false (0) value), and undef in scalar context. The next call to each after that will start iterating again. There is a single iterator for each hash, shared by all each, keys, and values function calls in the program; it can be reset by reading all the elements from the hash, or by evaluating keys HASH or values HASH. If you add or delete elements of a hash while you're iterating over it, you may get entries skipped or duplicated, so don't. Exception: It is always safe to delete the item most recently returned by each(), which means that the following code will work: while (($key, $value) = each %hash) { print $key, "\n"; delete $hash{$key}; # This is safe } The following prints out your environment like the printenv(1) program, only in a different order: while (($key,$value) = each %ENV) { print "$key=$value\n"; } See also keys, values and sort. Add by Pancho You can edit it here |
| Adding comments is available only for registered users. |
| Birth of a Hurricane
Summer storms are a regular feature in the North Atlantic, and while most pose little threat to our shores, a choice few become devastating hurricanes. To decipher which storms could bring danger, and which will not, atmospheric scientists are heading to the tropics to observe these systems as they form and dissipate--or develop into hurricanes. By learning to identify which weather systems are the most critical to track, the efforts may ultimately allow for earlier hurricane ...
|
PycckaR
BepcuR
Articles
Library
Downloads
