diff options
Diffstat (limited to 'erts/doc/src/erlang.xml')
| -rw-r--r-- | erts/doc/src/erlang.xml | 79 |
1 files changed, 73 insertions, 6 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index 46f8df4683..e90160dfd7 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -253,6 +253,54 @@ iolist() = [char() | binary() | iolist()] </desc> </func> <func> + <name>binary_part(Subject, PosLen) -> binary()</name> + <fsummary>Extracts a part of a binary</fsummary> + <type> + <v>Subject = binary()</v> + <v>PosLen = {Start,Length}</v> + <v>Start = int()</v> + <v>Length = int()</v> + </type> + <desc> + <p>Extracts the part of the binary described by <c>PosLen</c>.</p> + + <p>Negative length can be used to extract bytes at the end of a binary:</p> + +<code> +1> Bin = <<1,2,3,4,5,6,7,8,9,10>>. +2> binary_part(Bin,{byte_size(Bin), -5)). +<<6,7,8,9,10>> +</code> + + <p>If <c>PosLen</c> in any way references outside the binary, a <c>badarg</c> exception is raised.</p> + + <p><c>Start</c> is zero-based, i.e:</p> +<code> +1> Bin = <<1,2,3>> +2> binary_part(Bin,{0,2}). +<<1,2>> +</code> + + <p>See the STDLIB module <c>binary</c> for details about the <c>PosLen</c> semantics.</p> + + <p>Allowed in guard tests.</p> + </desc> + </func> + <func> + <name>binary_part(Subject, Start, Length) -> binary()</name> + <fsummary>Extracts a part of a binary</fsummary> + <type> + <v>Subject = binary()</v> + <v>Start = int()</v> + <v>Length = int()</v> + </type> + <desc> + <p>The same as <c>binary_part(Subject, {Pos, Len})</c>.</p> + + <p>Allowed in guard tests.</p> + </desc> + </func> + <func> <name>binary_to_atom(Binary, Encoding) -> atom()</name> <fsummary>Convert from text representation to an atom</fsummary> <type> @@ -318,6 +366,11 @@ iolist() = [char() | binary() | iolist()] corresponding to the bytes from position <c>Start</c> to position <c>Stop</c> in <c>Binary</c>. Positions in the binary are numbered starting from 1.</p> + + <note><p>This functions indexing style of using one-based indices for + binaries is deprecated. New code should use the functions in + the STDLIB module <c>binary</c> instead. They consequently + use the same (zero-based) style of indexing.</p></note> </desc> </func> <func> @@ -2749,7 +2802,7 @@ os_prompt%</pre> <item> <p>Works like <c>{spawn, Command}</c>, but only runs - external executables. The <c>Command</c> in it's whole + external executables. The <c>Command</c> in its whole is used as the name of the executable, including any spaces. If arguments are to be passed, the <c>args</c> and <c>arg0</c> <c>PortSettings</c> can be used.</p> @@ -2926,7 +2979,7 @@ os_prompt%</pre> The standard input and standard output handles of the port program will, if this option is supplied, be opened with the flag FILE_FLAG_OVERLAPPED, so that the port program can (and has to) do - overlapped I/O on it's standard handles. This is not normally + overlapped I/O on its standard handles. This is not normally the case for simple port programs, but an option of value for the experienced Windows programmer. <em>On all other platforms, this option is silently discarded</em>.</p> @@ -5105,7 +5158,7 @@ true</pre> </p> <p><em>NOTE:</em> If other programs on the system have bound to processors, e.g. another Erlang runtime system, you - may loose performance when binding schedulers. Therefore, + may lose performance when binding schedulers. Therefore, schedulers are by default not bound.</p> <p>Schedulers can be bound in different ways. The <c>How</c> argument determines how schedulers are bound. <c>How</c> can @@ -5850,9 +5903,23 @@ true</pre> </item> <tag><c>wordsize</c></tag> <item> - <p>Returns the word size in bytes as an integer, i.e. on a - 32-bit architecture 4 is returned, and on a 64-bit - architecture 8 is returned.</p> + <p>Same as <c>{wordsize, internal}</c></p> + </item> + <tag><c>{wordsize, internal}</c></tag> + <item> + <p>Returns the size of Erlang term words in bytes as an + integer, i.e. on a 32-bit architecture 4 is returned, + and on a pure 64-bit architecture 8 is returned. On a + halfword 64-bit emulator, 4 is returned, as the Erlang + terms are stored using a virtual wordsize of half the + systems wordsize.</p> + </item> + <tag><c>{wordsize, external}</c></tag> + <item> + <p>Returns the true wordsize of the emulator, i.e. the size + of a pointer, in bytes as an integer. On a pure 32-bit + architecture 4 is returned, on both a halfword and pure + 64-bit architecture, 8 is returned.</p> </item> </taglist> <note> |