How to Read a File in Char for C
Read a file graphic symbol past graphic symbol/UTF8
You are encouraged to solve this job according to the job description, using whatsoever language you may know.
- Chore
Read a file ane character at a fourth dimension, every bit opposed to reading the unabridged file at once.
The solution may exist implemented as a procedure, which returns the adjacent character in the file on each consecutive call (returning EOF when the end of the file is reached).
The process should support the reading of files containing UTF8 encoded broad characters, returning whole characters for each consecutive read.
- Related task
- Read a file line by line
Contents
- 1 Action!
- two AutoHotkey
- 3 BASIC256
- iv C
- v C++
- vi C#
- 7 Mutual Lisp
- 8 Crystal
- 9 Delphi
- ten Déjà Vu
- 11 Gene
- 12 FreeBASIC
- xiii FunL
- xiv Go
- 15 Haskell
- xvi J
- 17 Coffee
- xviii jq
- 19 Julia
- 20 Kotlin
- 21 Lua
- 22 M2000 Interpreter
- 23 Mathematica/Wolfram Language
- 24 NetRexx
- 25 Nim
- 26 Pascal
- 27 Perl
- 28 Phix
- 29 PicoLisp
- 30 Python
- 31 Racket
- 32 Raku
- 33 REXX
- 33.one version 1
- 33.two version 2
- 34 Band
- 35 Ruby-red
- 36 Run Bones
- 37 Rust
- 38 Seed7
- 39 Sidef
- twoscore Smalltalk
- 41 Tcl
- 42 Wren
- 43 zkl
Activeness! [edit]
byte XProc Main()
Open (i,"D:FILENAME.TXT",4,0)
Do
10=GetD(1)
Put(Ten)
Until EOF(one)
Od
Close(1)Return
AutoHotkey [edit]
File := FileOpen( "input.txt" , "r" )
while !File.AtEOF
MsgBox , % File.Read( 1 )
BASIC256 [edit]
f = freefile
filename$ = "file.txt"open f, filename$
while non eof(f)
print chr(readbyte(f));
end while
close f
end
C [edit]
#include <stdio.h>
#include <wchar.h>
#include <stdlib.h>
#include <locale.h>int main( void )
{
/* If your native locale doesn't employ UTF-8 encoding
* you demand to replace the empty string with a
* locale like "en_US.utf8"
*/
char *locale = setlocale (LC_ALL, "" ) ;
FILE *in = fopen ( "input.txt" , "r" ) ;wint_t c;
while ( (c = fgetwc (in) ) != WEOF)
putwchar (c) ;
fclose (in) ;return EXIT_SUCCESS;
}
C++ [edit]
#include <fstream>
#include <iostream>
#include <locale>using namespace std;
int main( void )
{
/* If your native locale doesn't use UTF-8 encoding
* you demand to replace the empty cord with a
* locale like "en_US.utf8"
*/
std:: locale :: global (std:: locale ( "" ) ) ; // for C++
std:: cout.imbue (std:: locale ( ) ) ;
ifstream in( "input.txt" ) ;wchar_t c;
while ( (c = in.become ( ) ) ! = in.eof ( ) )
wcout<<c;
in.close ( ) ;return EXIT_SUCCESS ;
}
C# [edit]
using System ;
using System.IO ;
using System.Text ;namespace RosettaFileByChar
{
class Program
{
static char GetNextCharacter(StreamReader streamReader) => ( char )streamReader. Read ( ) ;static void Main( string [ ] args)
{
Console. OutputEncoding = Encoding. UTF8 ;
char c;
using (FileStream fs = File. OpenRead ( "input.txt" ) )
{
using (StreamReader streamReader = new StreamReader(fs, Encoding. UTF8 ) )
{
while ( !streamReader. EndOfStream )
{
c = GetNextCharacter(streamReader) ;
Panel. Write (c) ;
}
}
}
}
}
}
Common Lisp [edit]
;; CLISP puts the external formats into a separate packet
#+clisp (import 'charset: utf- viii 'keyword)(with-open up-file (south "input.txt" : external-format : utf- viii )
(loop for c = (read-char due south nil )
while c
practice (format t "~a" c) ) )
Crystal [edit]
The encoding is UTF-8 by default, but it can be explicitly specified.
File.open ( "input.txt" ) do |file|
file.each_char { |c| p c }
end
or
File.open ( "input.txt" ) do |file|
while c = file.read_char
p c
finish
end
Delphi [edit]
program Read_a_file_character_by_character_UTF8;{$APPTYPE CONSOLE}
uses
Arrangement. SysUtils ,
System. Classes ;function GetNextCharacter(StreamReader: TStreamReader) : char ;
begin
Result : = chr (StreamReader. Read ) ;
end ;const
FileName: TFileName = 'input.txt' ;begin
if not FileExists (FileName) then
raise Exception. Create ( 'Error: File not exist.' ) ;var F : = TStreamReader. Create (FileName, TEncoding. UTF8 ) ;
while not F. EndOfStream do
begin
var c : = GetNextCharacter(F) ;
write (c) ;
terminate ;
readln;
end .
Déjà Vu [edit]
#helper function that deals with non-ASCII code points
local (read-utf8-char) file tmp:
!read-byte file
if = :eof dup:
drop
enhance :unicode-mistake
resize-blob tmp ++ dup len tmp
set-to tmp
attempt:
return !decode!utf-8 tmp
take hold of unicode-error:
if < 3 len tmp:
raise :unicode-error
(read-utf8-char) file tmp#reader role
read-utf8-char file:
!read-byte file
if = :eof dup:
return
local :tmp make-blob ane
fix-to tmp 0
effort:
return !decode!utf-8 tmp
grab unicode-fault:
(read-utf8-char) file tmp#if the module is used as a script, read from the file "input.txt",
#showing each code bespeak separately
if = (name) :(primary):
local :file !open :read "input.txt"while truthful:
read-utf8-char file
if = :eof dup:
drop
!close file
return
!.
Factor [edit]
USING: kernel io io.encodings.utf8 io.files strings ;
IN: rosetta-code.read-i"input.txt" utf8 [
[ read1 dup ] [ 1string write ] while drop
] with-file-reader
FreeBASIC [edit]
Dim As Long f
f = FreefileDim Equally String filename = "file.txt"
Dim As String*1 txtOpen filename For Binary Equally #f
While Not Eof (f)
txt = String ( Lof (f), 0 )
Become #f, , txt
Print txt;
Wend
Close #f
Slumber
FunL [edit]
import io.{InputStreamReader, FileInputStream} r = InputStreamReader( FileInputStream('input.txt'), 'UTF-8' )
while (ch = r.read()) != -1
print( chr(ch) )
r.close()
Go [edit]
package mainimport (
"bufio"
"fmt"
"io"
"bone"
)func Runer(r io.RuneReader) func () (rune, mistake) {
return func () (r rune, err mistake) {
r, _, err = r.ReadRune()
render
}
}func master() {
runes := Runer(bufio.NewReader(os.Stdin))
for r, err := runes(); err != null ; r,err = runes() {
fmt.Printf( "%c" , r)
}
}
Haskell [edit]
#!/usr/bin/env runhaskell{- The procedure to read a UTF-8 graphic symbol is only:
hGetChar :: Handle -> IO Char
bold that the encoding for the handle has been set to utf8.
-}import Arrangement.Surround (getArgs)
import System. IO (
Handle, IOMode ( .. ) ,
hGetChar, hIsEOF, hSetEncoding, stdin, utf8, withFile
)
import Control. Monad (grade_, unless)
import Text.Printf (printf)
import Information. Char (ord)processCharacters :: Handle -> IO ( )
processCharacters h = exercise
done <- hIsEOF h
unless done $ do
c <- hGetChar h
putStrLn $ printf "U+%04X" (ord c)
processCharacters hprocessOneFile :: Handle -> IO ( )
processOneFile h = exercise
hSetEncoding h utf8
processCharacters h{- Y'all can specify 1 or more files on the command line, or if no
files are specified, it reads from standard input.
-}
main :: IO ( )
primary = practise
args <- getArgs
case args of
[ ] -> processOneFile stdin
xs -> class_ xs $ \name -> do
putStrLn proper noun
withFile name ReadMode processOneFile
fustigate$ repeat €50 | ./read-char-utf8.hs U+20AC U+0035 U+0030 U+000A
J [edit]
Reading a file a character at a time is antithetical non only to the compages of J, only to the architecture and design of most computers and most file systems. Nevertheless, this can be a useful concept if you're building your own hardware. So permit's model it...
Beginning, we know that the kickoff viii-bit value in a utf-8 sequence tells united states of america the length of the sequence needed to represent that character. Specifically: we can convert that value to binary, and count the number of leading 1s to observe the length of the character (except the length is always at to the lowest degree ane graphic symbol long).
u8len=: 1 >. 0 i.~ ( 8#ii )#:a.&i.
So at present, we tin can apply indexed file read to read a utf-eight character starting at a specific file alphabetize. What we do is read the first octet and then read every bit many additional characters as we need based on any we started with. If that'southward not possible, nosotros will return EOF:
indexedread1u8=:4 :0
try.
octet0=. 1!:11 y;x,1
octet0,1!:11 y;( x+1 ),<:u8len octet0
take hold of.
'EOF'
end.
)
The length of the upshot tells us what to add to the file alphabetize to detect the adjacent available file index for reading.
Of course, this is massively inefficient. Then if someone ever asks you to do this, make sure you enquire them "Why?" Because the answer to that question is going to be important (and might advise a completely different implementation).
Note also that it would make more than sense to return an empty string, instead of the string 'EOF', when we reach the stop of the file. But that is out of scope for this chore.
Java [edit]
import coffee.io.FileReader ;
import java.io.IOException ;
import java.nio.charset.StandardCharsets ;public form Main {
public static void primary( String [ ] args) throws IOException {
var reader = new FileReader ( "input.txt", StandardCharsets.UTF_8 ) ;
while ( true ) {
int c = reader.read ( ) ;
if (c == - 1 ) intermission ;
System.out.print ( Character.toChars (c) ) ;
}
}
}
jq [edit]
jq being stream-oriented, it makes sense to define `readc` then that information technology emits a stream of the UTF-8 characters in the input:
def readc:
inputs + "\n" | explode[] | [.] | implode;
Example:
repeat '过活' | jq -Rn 'include "readc"; readc'
"过"
"活"
"\n"
Julia [edit]
The built-in read(stream, Char) role reads a unmarried UTF8-encoded character from a given stream.
open("myfilename") practice f
while !eof(f)
c = read(f, Char)
println(c)
end
cease Kotlin [edit]
// version one.1.2import java.io.File
const val EOF = -1
fun main(args: Array<Cord> ) {
val reader = File( "input.txt" ).reader ( ) // uses UTF-8 by default
reader.utilise {
while ( true ) {
val c = reader.read ( )
if (c == EOF) intermission
print(c.toChar ( ) ) // echo to console
}
}
}
Lua [edit]
-- Return whether the given string is a single ASCII character.
function is_ascii (str)
render string .match(str, "[\0-\x7F]" )
end-- Return whether the given string is an initial byte in a multibyte sequence.
part is_init (str)
render string .lucifer(str, "[\xC2-\xF4]" )
terminate-- Return whether the given string is a continuation byte in a multibyte sequence.
function is_cont (str)
return string .lucifer(str, "[\x80-\xBF]" )
end-- Accept a filestream.
-- Return the side by side UTF8 graphic symbol in the file.
function read_char (file)
local multibyte -- build a valid multibyte Unicode characterfor c in file:lines( ane ) practice
if is_ascii(c) then
if multibyte and then
-- Nosotros've finished reading a Unicode character; unread the adjacent byte,
-- and return the Unicode grapheme.
file: seek ( "cur" , - 1 )
return multibyte
else
return c
end
elseif is_init(c) then
if multibyte then
file: seek ( "cur" , - 1 )
return multibyte
else
multibyte = c
terminate
elseif is_cont(c) then
multibyte = multibyte .. c
else
assert ( imitation )
end
finish
end-- Test.
office read_all ( )
testfile = io.open up ( "tmp.txt" , "west" )
testfile: write ( "𝄞AöЖ€𝄞Ελληνικάy䮀成长汉\northward" )
testfile:shut( )
testfile = io.open ( "tmp.txt" , "r" )while truthful do
local c = read_char(testfile)
if non c then return else io.write ( " " , c) cease
end
end
𝄞 A ö Ж € 𝄞 Ε λ λ η ν ι κ ά y ä ® € 成 长 汉
M2000 Interpreter [edit]
from revision 27, version nine.iii, of M2000 Surroundings, Chinese 长 letter displayed in console (as displayed in editor)
Module checkit {
\\ prepare a file
\\ Save.Doc and Suspend.Medico to file, Load.Doc and Merge.Doc from file
document a$
a$={Starting time Line
Second line
Third Line
Ελληνικά Greek Letters
y䮀
成长汉
}
Save.Doc a$, "checkthis.txt", 2 ' 2 for UTF-8
b$="*"
final$=""
buffer Articulate bytes every bit byte*xvi
Buffer I as byte
Buffer Ii as byte*two
Buffer 3 equally byte*3
Locale 1033
open "checkthis.txt" for input as #f
seek#f, four ' skip BOM
While b$<>"" {
GetOneUtf8Char(&b$)
last$+=b$
}
close #f
Report final$
Sub GetOneUtf8Char(&ch$)
ch$=""
if Eof(#f) then Exit Sub
Get #f, I
Return Bytes, 0:=Eval(one, 0)
local mrk=Eval(1, 0)
Effort ok {
If Binary.And(mrk, 0xE0)=0xC0 so {
Get #f,one
Return Bytes, 1:=Eval$(one, 0,1)
ch$=Eval$(Bytes, 0, two)
} Else.if Binary.And(mrk, 0xF0)=0xE0 and then {
Get #f,2
Return Bytes, 1:=Eval$(two,0,2)
ch$=Eval$(Bytes, 0, iii)
} Else.if Binary.And(mrk, 0xF8)=0xF0 and so {
Get #f,3
Return Bytes, 1:=Eval$(three, 0, 3)
ch$=Eval$(Bytes, 0, 4)
} Else ch$=Eval$(Bytes, 0, 1)
}
if Error or not ok then ch$="" : exit sub
ch$=left$(string$(ch$ as Utf8dec),1)
Finish Sub
}
checkit
using certificate as final$
Module checkit {
\\ gear up a file
\\ Save.Doc and Append.Doc to file, Load.Doc and Merge.Dr. from file
document a$
a$={First Line
Second line
Third Line
Ελληνικά Greek Messages
y䮀
成长汉
}
Save.Doctor a$, "checkthis.txt", two ' 2 for UTF-8
b$="*"
certificate concluding$
buffer Clear bytes every bit byte*xvi
Buffer One as byte
Buffer 2 as byte*2
Buffer Iii every bit byte*3
Locale 1033
open "checkthis.txt" for input as #f
seek#f, 4 ' skip BOM
oldb$=""
While b$<>"" {
GetOneUtf8Char(&b$)
\\ if final$ is document and so 10 and 13 if comes alone are new line
\\ so we demand to throw x after the 13, so we have to use oldb$
if b$=chr$(10) so if oldb$=chr$(13) then oldb$="": go along
oldb$=b$
last$=b$ ' nosotros apply = for append to document
}
close #f
Report last$
Sub GetOneUtf8Char(&ch$)
ch$=""
if Eof(#f) then Exit Sub
Get #f, Ane
Return Bytes, 0:=Eval(one, 0)
local mrk=Eval(one, 0)
Effort ok {
If Binary.And(mrk, 0xE0)=0xC0 then {
Get #f,one
Return Bytes, 1:=Eval$(one, 0,ane)
ch$=Eval$(Bytes, 0, 2)
} Else.if Binary.And(mrk, 0xF0)=0xE0 then {
Get #f,two
Return Bytes, 1:=Eval$(2,0,2)
ch$=Eval$(Bytes, 0, iii)
} Else.if Binary.And(mrk, 0xF8)=0xF0 then {
Go #f,three
Return Bytes, 1:=Eval$(three, 0, 3)
ch$=Eval$(Bytes, 0, 4)
} Else ch$=Eval$(Bytes, 0, 1)
}
if Error or not ok so ch$="" : go out sub
ch$=left$(string$(ch$ as Utf8dec),i)
Cease Sub
}
checkit
Mathematica/Wolfram Linguistic communication [edit]
str = OpenRead["file.txt"];
ToString[Read[str, "Grapheme"], CharacterEncoding -> "UTF-eight"]
NetRexx [edit]
This instance is incorrect. Delight set the code and remove this message.
Details: Perhaps overengineered?
Java and by extension NetRexx provides I/O functions that read UTF-8 encoded character data direct from an attached input stream. The Reader.read() method reads a single character equally an integer value in the range 0 – 65535 [0x00 – 0xffff], reading from a file encoded in UTF-8 will read each codepoint into an int. In the sample below the readCharacters method reads the file character past grapheme into a Cord and returns the result to the caller. The rest of this sample examines the result and formats the details.
- The file information/utf8-001.txt information technology a UTF-8 encoded text file containing the following: y䮀𝄞𝄢12.
/* NetRexx */
options supersede format comments coffee crossref symbols nobinary
numeric digits 20runSample(arg)
render-- ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
method readCharacters(fName) public static binary returns String
slurped = String( '' )
slrp = StringBuilder( )
fr = Reader null
fFile = File(fName)
EOF = int -ane -- End Of File indicator
practise
fr = BufferedReader(FileReader(fFile) )
ic = int
cc = char
-- read the contents of the file one character at a time
loop label rdr forever
-- Reader.read reads a single grapheme every bit an integer value in the range 0 - 65535 [0x00 - 0xffff]
-- or -ane on cease of stream i.east. End Of File
ic = fr.read ( )
if ic == EOF and then go out rdr
cc = Rexx(ic).d2c
slrp.append (cc)
end rdr
-- load the results of the read into a variable
slurped = slrp.toString ( )
grab fex = FileNotFoundException
fex.printStackTrace ( )
take hold of iex = IOException
iex.printStackTrace ( )
finally
if fr \= naught then do
fr.close ( )
catch iex = IOException
iex.printStackTrace ( )
finish
end
render slurped-- ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
method encodingDetails(str = String) public static
stlen = str.length ( )
cplen = Character.codePointCount (str, 0, stlen)
say 'Unicode: length="'stlen'" code_point_count="'cplen'" cord="'str'"'
loop ix = 0 to stlen - 1
cp = Rexx(Character.codePointAt (str, nine) )
cc = Rexx(Character.charCount (cp) )
say ' 'formatCodePoint(ix, cc, cp)
if cc > 1 then practice
surrogates = [Rexx(Character.highSurrogate (cp) ).c2d ( ), Rexx(Grapheme.lowSurrogate (cp) ).c2d ( ) ]
loop sx = 0 to cc - i
ix = ix + sx
cp = surrogates[sx]
say ' 'formatCodePoint(ix, 1, cp)
end sx
cease
cease nine
say
return-- ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
-- @see http://docs.oracle.com/javase/6/docs/technotes/guides/intl/encoding.doc.html
-- @since Java 1.7
method formatCodePoint(ix, cc, cp) private static
scp = Rexx(Character.toChars (cp) )
icp = cp.d2x ( 8 ).x2d ( 9 ) -- signed to unsigned conversion
ocp = Rexx(Integer.toOctalString (icp) )
x_utf16 = ''
x_utf8 = ''
practise
b_utf16 = Cord(scp).getBytes ( 'UTF-16BE' )
b_utf8 = String(scp).getBytes ( 'UTF-8' )
loop bv = 0 to b_utf16.length - 1 by 2
x_utf16 = x_utf16 Rexx(b_utf16[bv] ).d2x ( two ) || Rexx(b_utf16[bv + 1 ] ).d2x ( ii )
end bv
loop bv = 0 to b_utf8.length - 1
x_utf8 = x_utf8 Rexx(b_utf8[bv] ).d2x ( 2 )
end bv
x_utf16 = x_utf16.infinite ( 1, ',' )
x_utf8 = x_utf8.space ( 1, ',' )
catch ex = UnsupportedEncodingException
ex.printStackTrace ( )
cease
cpName = Character.getName (cp)
fmt = -
'CodePoint:' -
'index="'9.correct ( 3, 0 ) '"' -
'character_count="'cc'"' -
'id="U+'cp.d2x ( v ) '"' -
'hex="0x'cp.d2x ( half-dozen ) '"' -
'dec="'icp.correct ( vii, 0 ) '"' -
'oct="'ocp.right ( 7, 0 ) '"' -
'char="'scp'"' -
'utf-sixteen="'x_utf16'"' -
'utf-viii="'x_utf8'"' -
'name="'cpName'"'
render fmt-- ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
method runSample(arg) public static
parse arg fileNames
if fileNames = '' and then fileNames = 'data/utf8-001.txt'
loop while fileNames \= ''
parse fileNames fileName fileNames
slurped = readCharacters(fileName)
say "Input:" slurped
encodingDetails(slurped)
end
say
return
Input: y䮀𝄞𝄢12 Unicode: length="10" code_point_count="8" string="y䮀𝄞𝄢12" CodePoint: index="000" character_count="1" id="U+00079" hex="0x000079" dec="0000121" oct="0000171" char="y" utf-16="0079" utf-viii="79" name="LATIN SMALL LETTER Y" CodePoint: index="001" character_count="1" id="U+000E4" hex="0x0000E4" dec="0000228" oct="0000344" char="ä" utf-sixteen="00E4" utf-eight="C3,A4" name="LATIN SMALL Letter A WITH DIAERESIS" CodePoint: alphabetize="002" character_count="one" id="U+000AE" hex="0x0000AE" dec="0000174" oct="0000256" char="®" utf-xvi="00AE" utf-8="C2,AE" name="REGISTERED SIGN" CodePoint: alphabetize="003" character_count="1" id="U+020AC" hex="0x0020AC" dec="0008364" oct="0020254" char="€" utf-16="20AC" utf-eight="E2,82,Air conditioning" proper name="EURO SIGN" CodePoint: index="004" character_count="2" id="U+1D11E" hex="0x01D11E" dec="0119070" oct="0350436" char="𝄞" utf-sixteen="D834,DD1E" utf-8="F0,9D,84,9E" proper noun="MUSICAL SYMBOL G CLEF" CodePoint: index="004" character_count="i" id="U+0D834" hex="0x00D834" dec="0055348" oct="0154064" char="?" utf-16="FFFD" utf-8="3F" name="HIGH SURROGATES D834" CodePoint: alphabetize="005" character_count="1" id="U+0DD1E" hex="0x00DD1E" dec="0056606" october="0156436" char="?" utf-sixteen="FFFD" utf-8="3F" name="LOW SURROGATES DD1E" CodePoint: index="006" character_count="ii" id="U+1D122" hex="0x01D122" dec="0119074" october="0350442" char="𝄢" utf-16="D834,DD22" utf-eight="F0,9D,84,A2" name="MUSICAL SYMBOL F CLEF" CodePoint: alphabetize="006" character_count="one" id="U+0D834" hex="0x00D834" december="0055348" october="0154064" char="?" utf-xvi="FFFD" utf-eight="3F" proper noun="HIGH SURROGATES D834" CodePoint: index="007" character_count="1" id="U+0DD22" hex="0x00DD22" dec="0056610" oct="0156442" char="?" utf-sixteen="FFFD" utf-8="3F" proper name="LOW SURROGATES DD22" CodePoint: index="008" character_count="1" id="U+00031" hex="0x000031" dec="0000049" oct="0000061" char="one" utf-sixteen="0031" utf-eight="31" proper noun="DIGIT ONE" CodePoint: index="009" character_count="1" id="U+00032" hex="0x000032" december="0000050" oct="0000062" char="2" utf-xvi="0032" utf-eight="32" name="DIGIT TWO"
Nim [edit]
Equally virtually organization languages, Nim reads bytes and provides functions to decode bytes into Unicode runes. The normal mode to read a stream of UTF-8 characters would exist to read the file line by line and decode each line using the "utf-8" iterator which yields UTF-viii characters every bit strings (ane by 1) or using the "runes" iterator which yields the UTF-eight characters as Runes (one by one).
Equally in fact the file would be read line by line, even if the characters are actually yielded one by i, it may be considered as cheating. So, we provide a office and an iterator which read bytes one past ane.
import unicodeproc readUtf8(f: File): cord =
## Return next UTF-eight grapheme every bit a string.
while truthful:
issue.add f.readChar()
if result.validateUtf8() == -1: pauseiterator readUtf8(f: File): cord =
## Yield successive UTF-8 characters from file "f".
var res: string
while not f.endOfFile:
res.setLen(0)
while true:
res.add together f.readChar()
if res.validateUtf8() == -i: break
yield res
Pascal [edit]
(* Read a file char past char *)
program ReadFileByChar;
var
InputFile,OutputFile: file of char ;
InputChar: char ;
brainstorm
Assign(InputFile, 'testin.txt' ) ;
Reset(InputFile) ;
Assign(OutputFile, 'testout.txt' ) ;
Rewrite(OutputFile) ;
while not Eof (InputFile) do
begin
Read (InputFile, InputChar) ;
Write (OutputFile, InputChar)
end ;
Close(InputFile) ;
Shut(OutputFile)
end .
Perl [edit]
binmode STDOUT , ':utf8' ; # so we can print broad chars without warningopen my $fh , "<:encoding(UTF-8)" , "input.txt" or die "$!\n" ;
while ( read $fh , my $char , 1 ) {
printf "got grapheme $char [U+%04x]\n" , ord $char ;
}shut $fh ;
If the contents of the input.txt file are aă€⼥ and so the output would be:
got graphic symbol a [U+0061] got character ă [U+0103] got character € [U+20ac] got graphic symbol ⼥ [U+2f25]
Phix [edit]
By and large I utilise utf8_to_utf32() on whole lines when I want to do character-counting.
Y'all can observe that routine in builtins/utfconv.eastward, and here is a modified copy that reads precisely one unicode graphic symbol from a file. If there is a genuine demand for information technology, I could hands add this to that file permanently, and document/autoinclude it properly.
constant INVALID_UTF8 = #FFFD function get_one_utf8_char ( integer fn ) -- returns INVALID_UTF8 on error, else a string of 1..4 bytes representing 1 character object res integer headb , bytes , c -- headb = showtime byte of utf-8 character: headb = getc ( fn ) if headb =- 1 then return - i terminate if res = "" & headb -- calculate length of utf-8 character in bytes (one..four): if headb < 0 then bytes = 0 -- (utf-8 starts at #0) elsif headb <= 0b01111111 then bytes = ane -- 0b_0xxx_xxxx elsif headb <= 0b10111111 then bytes = 0 -- (it's a tail byte) elsif headb <= 0b11011111 so bytes = 2 -- 0b_110x_xxxx elsif headb <= 0b11101111 and then bytes = 3 -- 0b_1110_xxxx elsif headb <= 0b11110100 so bytes = 4 -- 0b_1111_0xzz else bytes = 0 -- (utf-viii ends at #10FFFF) end if -- 2..4 bytes encoding (tail range: 0b_1000_0000..0b_1011_1111); for j = 1 to bytes - 1 do -- tail bytes are valid? c = getc ( fn ) if c < #eighty or c > #BF then bytes = 0 -- invalid tail byte or eof exit stop if res &= c end for -- 1 byte encoding (head range: 0b_0000_0000..0b_0111_1111): if bytes = i then c = headb -- UTF-viii = ASCII -- ii bytes encoding (caput range: 0b_1100_0000..0b_1101_1111): elsif bytes = ii so c = and_bits ( headb , #1F )* #40 + -- 0b110[7..11] headb and_bits ( res [ 2 ], #3F ) -- 0b10[1..6] tail if c > #7FF then ? nine / 0 end if -- sanity bank check if c < #eighty then -- long form? res = INVALID_UTF8 finish if -- 3 bytes encoding (head range: 0b_1110_0000..0b_1110_1111): elsif bytes = three then c = and_bits ( headb , #0F )* #1000 + -- 0b1110[13..xvi] head and_bits ( res [ 2 ], #3F )* #40 + -- 0b10[seven..12] tail and_bits ( res [ 3 ], #3F ) -- 0b10[1..6] tail if c > #FFFF and so ? 9 / 0 end if -- sanity check if c < #800 -- long form? or ( c >= #D800 and c <= #DFFF ) and then -- utf-16 incompatible res = INVALID_UTF8 end if -- 4 bytes encoding (caput range: 0b_1111_0000..0b_1111_0111): elsif bytes = 4 then c = and_bits ( headb , #07 )* #040000 + -- 0b11110[19..21] caput and_bits ( res [ 2 ], #3F )* #k + -- 0b10[thirteen..18] tail and_bits ( res [ 3 ], #3F )* #0040 + -- 0b10[vii..12] tail and_bits ( res [ 4 ], #3F ) -- 0b10[1..6] tail if c < #10000 -- long form? or c > #10FFFF so res = INVALID_UTF8 -- utf-8 ends at #10FFFF end if -- bytes = 0; electric current byte is not encoded correctly: else res = INVALID_UTF8 end if return res end role
Test lawmaking:
--string utf8 = "aă€⼥" -- (aforementioned results equally next) string utf8 = utf32_to_utf8 ({ #0061 , #0103 , #20ac , #2f25 }) printf ( 1 , "length of utf8 is %d bytes\northward" , length ( utf8 )) integer fn = open up ( "test.txt" , "wb" ) puts ( fn , utf8 ) close ( fn ) fn = open ( "test.txt" , "r" ) for i = 1 to 5 do object res = get_one_utf8_char ( fn ) if string ( res ) then if platform ()= LINUX then printf ( one , "char %d (%s) is %d bytes\due north" ,{ i , res , length ( res )}) else -- unicode and consoles tricky on windows, so I'm -- just fugitive that effect altogther (t)here. printf ( 1 , "char %d is %d bytes\n" ,{ i , length ( res )}) end if elsif res =- 1 then printf ( 1 , "char %d - EOF\due north" , i ) exit else printf ( 1 , "char %d - INVALID_UTF8\due north" , i ) exit terminate if end for close ( fn )
length of utf8 is 9 bytes char 1 is i bytes char 2 is 2 bytes char iii is iii bytes char iv is 3 bytes char 5 - EOF
PicoLisp [edit]
Pico Lisp uses UTF-eight until told otherwise.
(in "wordlist"
(while (char)
(process @))
Python [edit]
def get_next_character(f):
# note: assumes valid utf-eight
c = f.read ( 1 )
while c:
while True:
try:
yield c.decode ( 'utf-8' )
except UnicodeDecodeError:
# we've encountered a multibyte grapheme
# read another byte and effort once more
c += f.read ( one )
else:
# c was a valid char, and was yielded, go on
c = f.read ( i )
intermission# Usage:
with open ( "input.txt" , "rb" ) as f:
for c in get_next_character(f):
print (c)
Python 3 simplifies the handling of text files since you can specify an encoding.
def get_next_character(f):
"""Reads one character from the given textfile"""
c = f.read ( 1 )
while c:
yield c
c = f.read ( 1 )# Usage:
with open ( "input.txt" , encoding= "utf-8" ) as f:
for c in get_next_character(f):
print (c, sep= "" , cease= "" )
Racket [edit]
Don't nosotros all love self reference?
#lang noise
; This file contains utf-8 charachters: λ, α, γ ...
(for ([c (in-port read-char (open-input-file "read-file.rkt"))])
(brandish c))
Output:
#lang racket
; This file contains utf-viii charachters: λ, α, γ ...
(for ([c (in-port read-char (open-input-file "read-file.rkt"))])
(brandish c))
Raku [edit]
(formerly Perl 6)
Raku has a built in method .getc to get a single character from an open up file handle. File handles default to UTF-viii, so they will handle multi-byte characters correctly.
To read a single character at a time from the Standard Input terminal; $*IN in Raku:
. say while defined $_ = $*IN . getc ;
Or, from a file:
my $filename = 'whatever' ;my $in = open( $filename , :r ) orelse . dice ;
print $_ while divers $_ = $in . getc ;
REXX [edit]
version ane [edit]
REXX doesn't support UTF8 encoded wide characters, just bytes.
The task'south requirement stated that EOF was to be returned upon reaching the terminate-of-file, so this programming case was written every bit a subroutine (procedure).
Notation that displaying of characters that may modify screen beliefs such as tab usage, backspaces, line feeds, carriage returns, "bells" and others are suppressed, but their hexadecimal equivalents are displayed.
/*REXX program reads and displays a file char by char, returning 'EOF' when washed. */
parse arg iFID . /*iFID: is the fileID to be read. */
/* [↓] show the file'southward contents. */
if iFID\=='' and so practise j=one until ten=='EOF' /*J count's the file'due south characters. */
x=getchar(iFID); y= /*go a character or an 'EOF'. */
if x>> ' ' then y=ten /*brandish X if presentable. */
say right (j, 12 ) 'character, (hex,char)' c2x (x) y
end /*j*/ /* [↑] only brandish X if not low hex*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
getchar: procedure; parse arg z; if chars (z)==0 so return 'EOF'; render charin (z)
input file: ABC
and was created by the DOS command (nether Windows/XP): repeat 123 [¬ a prime]> ABC
123 [¬ a prime]
output (for the above [ABC] input file:
1 graphic symbol, (hex,char) 31 1 2 character, (hex,char) 32 ii iii character, (hex,char) 33 3 4 character, (hex,char) twenty five graphic symbol, (hex,char) 5B [ half-dozen character, (hex,char) AA ¬ 7 character, (hex,char) 20 8 grapheme, (hex,char) 61 a 9 character, (hex,char) twenty 10 character, (hex,char) lxx p 11 character, (hex,char) 72 r 12 character, (hex,char) 69 i 13 grapheme, (hex,char) 6D grand 14 grapheme, (hex,char) 65 e xv character, (hex,char) 5D ] sixteen character, (hex,char) 0D 17 character, (hex,char) 0A 18 graphic symbol, (hex,char) 454F46 EOF End-Of-File.
version 2 [edit]
/* REXX ---------------------------------------------------------------
* 29.12.2013 Walter Pachl
* read one utf8 grapheme at a time
* run across http://de.wikipedia.org/wiki/UTF-8#Kodierung
*--------------------------------------------------------------------*/
oid='utf8.txt';'erase' oid /* outset create file containing utf8 chars*/
Phone call charout oid,'79'ten
Call charout oid,'C3A4'x
Phone call charout oid,'C2AE'10
Call charout oid,'E282AC'10
Call charout oid,'F09D849E'x
Phone call lineout oid
fid='utf8.txt' /* so read information technology and evidence the contents */
Exercise Until c8='EOF'
c8=get_utf8char(fid)
Say left (c8,4 ) c2x (c8)
End
Exitget_utf8char: Procedure
Parse Arg f
If chars (f)=0 And then
Return 'EOF'
c=charin (f)
b=c2b(c)
If left (b,1 )=0 Then
Nop
Else Exercise
p=pos ( '0',b)
Exercise i=1 To p-2
If chars (f)=0 Then Practice
Say 'illegal contents in file' f
Leave
Terminate
c=c|| charin (f)
Terminate
Terminate
Render cc2b: Render x2b ( c2x ( arg ( 1 ) ) )
output:
y 79 ä C3A4 ® C2AE € E282AC � F09D849E EOF 454F46
Ring [edit]
fp = fopen("C:\Ring\ReadMe.txt","r")
r = fgetc(fp)
while isstring(r)
r = fgetc(fp)
encounter r
end
fclose(fp)
Output:
================================================== The Ring Programming Language http://ring-lang.net/ Version 1.0 Release Date : Jan 25, 2016 Update Engagement : March 27, 2016 =================================================== Binary release for Microsoft Windows =================================================== Run Starting time.bat to open Ring Notepad then showtime learning from the documentation Bring together Ring Group for questions https://groups.google.com/forum/#!forum/band-lang Greetings, Mahmoud Fayed [email protected] http://www.facebook.com/mahmoudfayed1986
Reddish [edit]
File.open up ( 'input.txt', 'r:utf-8' ) practice |f|
f.each_char { |c| p c}
end
or
File.open up ( 'input.txt', 'r:utf-eight' ) do |f|
while c = f.getc
p c
end
end
Run Basic [edit]
open file.txt" for binary equally #f
numChars = 1 ' specify number of characters to read
a$ = input$(#f,numChars) ' read number of characters specified
b$ = input$(#f,one) ' read i character
shut #f
Rust [edit]
Rust standard library provides hardly any straight-forwards manner to read single UTF-8 characters from a file. Following code implements an iterator that consumes a byte stream, taking only equally many bytes as necessary to decode the next UTF-8 character. It provides quite a complete fault report, and then that the client code tin leverage it to deal with corrupted input.
The decoding code is based on utf8-decode crate originally.
utilise std::{
catechumen::TryFrom,
fmt::{Debug, Display, Formatter},
io::Read,
}; pub struct ReadUtf8<I: Iterator> {
source: std::iter::Peekable<I>,
}
impl<R: Read> From<R> for ReadUtf8<std::io::Bytes<R>> {
fn from(source: R) -> Cocky {
ReadUtf8 {
source: source.bytes().peekable(),
}
}
}
impl<I, East> Iterator for ReadUtf8<I>
where
I: Iterator<Item = Result<u8, Eastward>>,
{
type Detail = Outcome<char, Fault<E>>;
fn side by side(&mut self) -> Selection<Self::Item> {
self.source.next().map(|next| match next {
Ok(lead) => cocky.complete_char(atomic number 82),
Err(e) => Err(Error::SourceError(e)),
})
}
}
impl<I, East> ReadUtf8<I>
where
I: Iterator<Particular = Result<u8, E>>,
{
fn continuation(&mut self) -> Result<u32, Mistake<E>> {
if allow Some(Ok(byte)) = self.source.peek() {
let byte = *byte;
render if byte & 0b1100_0000 == 0b1000_0000 {
cocky.source.adjacent();
Ok((byte & 0b0011_1111) every bit u32)
} else {
Err(Error::InvalidByte(byte))
};
}
match self.source.next() {
None => Err(Fault::InputTruncated),
Some(Err(due east)) => Err(Error::SourceError(e)),
Some(Ok(_)) => unreachable!(),
}
}
fn complete_char(&mut self, pb: u8) -> Effect<char, Fault<E>> {
let a = lead as u32; // Let'due south name the bytes in the sequence
let result = if a & 0b1000_0000 == 0 {
Ok(a)
} else if lead & 0b1110_0000 == 0b1100_0000 {
let b = self.continuation()?;
Ok((a & 0b0001_1111) << 6 | b)
} else if a & 0b1111_0000 == 0b1110_0000 {
let b = cocky.continuation()?;
permit c = cocky.continuation()?;
Ok((a & 0b0000_1111) << 12 | b << 6 | c)
} else if a & 0b1111_1000 == 0b1111_0000 {
permit b = self.continuation()?;
let c = cocky.continuation()?;
permit d = self.continuation()?;
Ok((a & 0b0000_0111) << 18 | b << 12 | c << 6 | d)
} else {
Err(Error::InvalidByte(lead))
};
Ok(char::try_from(result?).unwrap())
}
}
#[derive(Debug, Clone)]
pub enum Mistake<E> {
InvalidByte(u8),
InputTruncated,
SourceError(E),
}
impl<E: Display> Display for Fault<Due east> {
fn fmt(&cocky, f: &mut Formatter<'_>) -> std::fmt::Outcome {
lucifer self {
Cocky::InvalidByte(b) => write!(f, "invalid byte 0x{:ten}", b),
Self::InputTruncated => write!(f, "character truncated"),
Self::SourceError(east) => e.fmt(f),
}
}
}
fn main() -> std::io::Result<()> {
for (index, value) in ReadUtf8::from(std::fs::File::open("test.txt")?).enumerate() {
match value {
Ok(c) => impress!("{}", c),
Err(eastward) => {
print!("\u{fffd}");
eprintln!("offset {}: {}", index, e);
}
}
}
Ok(())
}
Seed7 [edit]
The library utf8.s7i provides the functions openUtf8 and getc. When a file has been opened with openUtf8 fhe function getc reads UTF-8 characters from the file. To allow writing Unicode characters to standard output the file STD_UTF8_OUT is used.
$ include "seed7_05.s7i";
include "utf8.s7i";const proc: chief is func
local
var file: inFile is STD_NULL;
var char: ch is ' ';
begin
OUT := STD_UTF8_OUT;
inFile := openUtf8("readAFileCharacterByCharacterUtf8.in", "r");
if inFile <> STD_NULL and then
while hasNext(inFile) practice
ch := getc(inFile);
writeln("got graphic symbol " <& ch <& " [U+" <& ord(ch) radix 16 <& "]");
end while;
shut(inFile);
finish if;
end func;
When the input file readAFileCharacterByCharacterUtf8.in contains the characters aă€⼥ the output is:
got character a [U+61] got graphic symbol ă [U+103] got graphic symbol € [U+20ac] got character ⼥ [U+2f25]
Sidef [edit]
var file = File ( 'input.txt' ) # the input file contains: "aă€⼥"
var fh = file.open_r # equivalent with: file.open('<:utf8')
fh.each_char { |char|
printf ( "got character #{char} [U+%04x]\n", char.ord )
}
got character a [U+0061] got character ă [U+0103] got graphic symbol € [U+20ac] got character ⼥ [U+2f25]
Smalltalk [edit]
|utfStream|
utfStream := 'input' asFilename readStream asUTF8EncodedStream.
[ utfStream atEnd] whileFalse:[
Transcript showCR:'got char ',utfStream next.
].
utfStream close.
Tcl [edit]
To read a single grapheme from a file, use:
set up ch [ read $channel 1 ]
This will read multiple bytes sufficient to obtain a Unicode grapheme if a suitable encoding has been configured on the channel. For binary channels, this will always eat exactly one byte. However, the depression-level channel buffering logic may eat more than ane byte (which but really matters where the channel is being handed on to some other procedure and the channel is over a file descriptor that doesn't support the lseek Os phone call); the extent of buffering can be controlled via:
fconfigure $channel -buffersize $byteCount
When the channel is only being accessed from Tcl (or via Tcl'southward C API) it is not normally necessary to adjust this selection.
Wren [edit]
import "io" for FileFile. open up ( "input.txt" ) { |file|
var offset = 0
var char = "" // stores each byte read till we have a complete UTF encoded character
while ( truthful ) {
var b = file. readBytes ( 1 , offset)
if (b == "" ) return // stop of stream
char = char + b
if ( char . codePoints [ 0 ] >= 0 ) { // a UTF encoded character is consummate
System. write ( char ) // print information technology
char = "" // reset shop
}
showtime = start + i
}
}
zkl [edit]
zkl doesn't know much about UTF-viii or Unicode simply is able to examination whether a string or number is valid UTF-8 or not. This code uses that to build a state machine to decode a byte stream into UTF-8 characters.
fcn readUTF8c(chr,s=""){ // transform UTF-8 character stream
s+=chr;
try{ s.len(8); return(s) }
take hold of{ if(s.len()>half-dozen) throw(__exception) } // 6 bytes max for UTF-8
return(Void.Again,south); // phone call me again with southward & another character
} Used to modify a zkl iterator, it can consume whatever stream-able (files, strings, lists, etc) and provides support for foreach, map, look ahead, button dorsum, etc.
fcn utf8Walker(obj){
obj.walker(3) // read characters
.tweak(readUTF8c)
} s:="-->\u20AC123"; // --> e2,82,ac,31,32,33 == -->€123
utf8Walker(s).walk().println();w:=utf8Walker(Data(Void,s,"\n")); // Data is a byte bucket
foreach c in (utf8Walker(Data(Void,s,"\n"))){ print(c) }utf8Walker(Data(Void,0xe2,0x82,"123456")).walk().println(); // € is short one byte
L("-","-",">","€","1","2","three") -->€123 VM#1 defenseless this unhandled exception: ValueError : Invalid UTF-8 string If you lot wish to push button a UTF-8 stream through one or more functions, y'all can apply the same country machine:
stream:=Data(Void,s,"\n").howza(three); // character stream
stream.pump(Listing,readUTF8c,"print")
-->€123
and returns a list of the viii UTF-8 characters (with newline). Or, if file "foo.txt" contains the characters:
File("foo.txt","rb").howza(three).pump(List,readUTF8c,"print"); produces the same result.
Source: http://www.rosettacode.org/wiki/Read_a_file_character_by_character/UTF8
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