String Byte Length: Difference between revisions
→{{header|Python}}: UTF-16: extra 2 bytes is probably Unicode BOM |
|||
Line 271:
assert len(s) == 5
assert len(s.encode('UTF-8')) == 7
assert len(s.encode('UTF-16')) == 12 #
=={{header|Ruby}}==
|
Revision as of 02:20, 12 December 2007
You are encouraged to solve this task according to the task description, using any language you may know.
In this task, the goal is to find the byte length of a string. This means encodings like UTF-8 may need to be handled specially, as there is not necessarily a one-to-one relationship between bytes and characters, and some languages recognize this. For example, the character length of "møøse" is 5 but the byte length is 7 in UTF-8 and 10 in UTF-16.
For character length, see String Character Length.
4D
$length:=Length("Hello, world!")
Ada
Compiler: GCC 4.1.2
Str : String := "Hello World"; Length : constant Natural := Str'Size / System.Storage_Unit;
The 'size attribute returns the size of an object in bits. System.Storage_Unit is the number of bits in a byte on the current machine.
AppleScript
count of "Hello World"
AWK
From within any code block:
w=length("Hello, world!") # static string example x=length("Hello," s " world!") # dynamic string example y=length($1) # input field example z=length(s) # variable name example
Ad hoc program from command line:
echo "Hello, wørld!" | awk '{print length($0)}' # 14
From executable script: (prints for every line arriving on stdin)
#!/usr/bin/awk -f {print"The length of this line is "length($0)}
C
Compiler: GCC 3.3.3
#include <string.h> int main(void) { const char *string = "Hello, world!"; size_t length = strlen(string); return 0; }
or by hand:
int main(void) { const char *string = "Hello, world!"; size_t length = 0; char *p = (char *) string; while (*p++ != '\0') length++; return 0; }
or (for arrays of char only)
#include <stdlib.h> int main(void) { char const s[] = "Hello, world!"; size_t length = sizeof s - 1; return 0; }
C++
Standard: ISO C++ (AKA C++98):
Compiler: g++ 4.0.2
#include <string> // note: not <string.h> int main() { std::string s = "Hello, world!"; std::string::size_type length = s.length(); // option 1: In Characters/Bytes std::string::size_type size = s.size(); // option 2: In Characters/Bytes // In bytes same as above since sizeof(char) == 1 std::string::size_type bytes = s.length() * sizeof(std::string::value_type); }
For wide character strings:
#include <string> int main() { std::wstring s = L"\u304A\u306F\u3088\u3046"; std::wstring::size_type length = s.length() * sizeof(std::wstring::value_type); // in bytes }
C#
Platform: .NET Language Version: 1.0+
string s = "Hello, world!"; int blength = System.Text.Encoding.GetBytes(s).length; // In Bytes.
Clean
Clean Strings are unboxed arrays of characters. Characters are always a single byte. The function size returns the number of elements in an array.
import StdEnv strlen :: String -> Int strlen string = size string Start = strlen "Hello, world!"
ColdFusion
#len("Hello World")#
Common Lisp
(length "Hello World")
Component Pascal
LEN("Hello, World!")
Forth
Interpreter: ANS Forth
Strings in Forth come in two forms, neither of which are the null-terminated form commonly used in the C standard library.
Counted string
A counted string is a single pointer to a short string in memory. The string's first byte is the count of the number of characters in the string. This is how symbols are stored in a Forth dictionary.
CREATE s ," Hello world" \ create string "s" s C@ ( -- length=11 )
Stack string
A string on the stack is represented by a pair of cells: the address of the string data and the length of the string data (in characters). The word COUNT converts a counted string into a stack string. The STRING utility wordset of ANS Forth works on these addr-len pairs. This representation has the advantages of not requiring null-termination, easy representation of substrings, and not being limited to 255 characters.
S" string" ( addr len) DUP . \ 6
Haskell
It is not possible to determine the "byte length" of an ordinary string, because in Haskell, a string is a boxed list of unicode characters. So each character in a string is represented as whatever the compiler considers as the most efficient representation of a cons-cell and a unicode character, and not as a byte.
For efficient storage of sequences of bytes, there's Data.ByteString, which uses Word8 as a base type. Byte strings have an additional Data.ByteString.Char8 interface, which will truncate each Unicode Char to 8 bits as soon as it is converted to a byte string. However, this is not adequate for the task, because truncation simple will garble characters other than Latin-1, instead of encoding them into UTF-8, say.
There are several (non-standard, so far) Unicode encoding libraries available on Hackage. As an example, we'll use encoding-0.2, as Data.Encoding:
import Data.Encoding import Data.ByteString as B strUTF8 :: ByteString strUTF8 = encode UTF8 "Hello World!" strUTF32 :: ByteString strUTF32 = encode UTF32 "Hello World!" strlenUTF8 = B.length strUTF8 strlenUTF32 = B.length strUTF32
IDL
Compiler: any IDL compiler should do
length = strlen("Hello, world!")
Java
Java encodes strings in UTF-16, which represents each character with one or two 16-bit values. The length method of String objects returns the number of 16-bit values used to encode a string, so the number of bytes can be determined by doubling that number.
String s = "Hello, world!"; int byteCount = s.length() * 2;
Another way to know the byte length of a string is to explicitly specify the charset we desire.
String s = "Hello, world!"; int byteCountUTF16 = s.getBytes("UTF-16").length; int byteCountUTF8 = s.getBytes("UTF-8").length;
JavaScript
JavaScript encodes strings in UTF-16, which represents each character with one or two 16-bit values. The length property of string objects gives the number of 16-bit values used to encode a string, so the number of bytes can be determined by doubling that number.
var s = "Hello, world!"; var byteCount = s.length * 2; //26
JudoScript
//Store length of hello world in length and print it . length = "Hello World".length();
LSE64
LSE stores strings as arrays of characters in 64-bit cells plus a count.
" Hello world" @ 1 + 8 * , # 96 = (11+1)*(size of a cell) = 12*8
Lua
Interpreter: Lua 5.0 or later.
string="Hello world" length=#string
mIRC Scripting Language
alias stringlength { echo -a Your Name is: $len($$?="Whats your name") letters long! }
OCaml
Interpreter/Compiler: Ocaml 3.09
String.length "Hello world";;
Perl
Interpreter: perl 5.8
Strings in Perl consist of characters. Measuring the byte length therefore requires conversion to some binary representation (called encoding, both noun and verb).
use utf8; # so we can use literal characters like ☺ in source use Encode qw(encode); print length encode 'UTF-8', "Hello, world! ☺"; # 17. The last character takes 3 bytes, the others 1 byte each. print length encode 'UTF-16', "Hello, world! ☺"; # 32. 2 bytes for the BOM, then 15 byte pairs for each character.
PHP
$length = strlen('Hello, world!');
PL/SQL
DECLARE string VARCHAR2( 50 ) := 'Hello, world!'; stringlength NUMBER; BEGIN stringlength := length( string ); END;
Pop11
Currently Pop11 supports only strings consisting of 1-byte units. Strings can carry arbitrary binary data, so user can for example use UTF-8 (however builtin procedures will treat each byte as a single character). The length function for strings returns length in bytes:
lvars str = 'Hello, world!'; lvars len = length(str);
Python
Interpreter: Python 2.x
Byte length depends on the encoding. Python use 2 or 4 bytes per character internally for unicode strings, depending on how it was built. The internal representation is not interesting for the user.
# The letter Alef >>> len(u'\u05d0'.encode('utf-8')) 2 >>> len(u'\u05d0'.encode('iso-8859-8')) 1
Example from the problem statement:
#!/bin/env python # -*- coding: UTF-8 -*- s = u"møøse" assert len(s) == 5 assert len(s.encode('UTF-8')) == 7 assert len(s.encode('UTF-16')) == 12 # The extra character is probably a leading Unicode byte-order mark (BOM).
Ruby
string="Hello world" print string.length
or
puts "Hello World".length
Scheme
(string-length "Hello world")
Smalltalk
string := 'Hello, world!". string size.
Standard ML
Interpreter: SML/NJ 110.60, Moscow ML 2.01 (January 2004)
Compiler: MLton 20061107
val strlen = size "Hello, world!";
Tcl
Basic version:
string bytelength "Hello, world!"
or more elaborately, needs Interpreter any 8.X. Tested on 8.4.12.
fconfigure stdout -encoding utf-8; #So that Unicode string will print correctly set s1 "hello, world" set s2 "\u304A\u306F\u3088\u3046" puts [format "length of \"%s\" in bytes is %d" $s1 [string bytelength $s1]] puts [format "length of \"%s\" in bytes is %d" $s2 [string bytelength $s2]]
Toka
" hello, world!" string.getLength
UNIX Shell
With external utilities:
Interpreter: any bourne shell
string='Hello, world!' length=`echo -n "$string" | wc -c | tr -dc '0-9'` echo $length # if you want it printed to the terminal
With SUSv3 parameter expansion modifier:
Interpreter: Almquist SHell (NetBSD 3.0), Bourne Again SHell 3.2, Korn SHell (5.2.14 99/07/13.2), Z SHell
string='Hello, world!' length="${#string}" echo $length # if you want it printed to the terminal
VBScript
LenB(string|varname)
Returns the number of bytes required to store a string in memory Returns null if string|varname is null
xTalk
Interpreter: HyperCard
put the length of "Hello World"
or
put the number of characters in "Hello World"
- Split and Needing Review
- Programming Tasks
- Solutions by Programming Task
- 4D
- Ada
- AppleScript
- AppleScript examples needing attention
- Examples needing attention
- AWK
- C
- C++
- C sharp
- Clean
- ColdFusion
- ColdFusion examples needing attention
- Common Lisp
- Common Lisp examples needing attention
- Component Pascal
- Component Pascal examples needing attention
- Forth
- Haskell
- IDL
- IDL examples needing attention
- Java
- JavaScript
- JudoScript
- JudoScript examples needing attention
- LSE64
- Lua
- Lua examples needing attention
- MIRC Scripting Language
- MIRC Scripting Language examples needing attention
- OCaml
- OCaml examples needing attention
- Perl
- PHP
- PHP examples needing attention
- PL/SQL
- PL/SQL examples needing attention
- Pop11
- Python
- Ruby
- Scheme
- Scheme examples needing attention
- Smalltalk
- Smalltalk examples needing attention
- Standard ML
- Standard ML examples needing attention
- Tcl
- Toka
- UNIX Shell
- VBScript
- XTalk
- XTalk examples needing attention