Check that file exists
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You are encouraged to solve this task according to the task description, using any language you may know.
In this task, the job is to verify that a file called "input.txt" and the directory called "docs" exist. This should be done twice: once for the current working directory and once for a file and a directory in the filesystem root.
Optional criteria (May 2015): verify it works with 0-length files; and with an unusual filename: `Abdu'l-Bahá.txt
Ada
This example should work with any Ada 95 compiler. <lang ada>with Ada.Text_IO; use Ada.Text_IO;
procedure File_Exists is
function Does_File_Exist (Name : String) return Boolean is The_File : Ada.Text_IO.File_Type; begin Open (The_File, In_File, Name); Close (The_File); return True; exception when Name_Error => return False; end Does_File_Exist;
begin
Put_Line (Boolean'Image (Does_File_Exist ("input.txt" ))); Put_Line (Boolean'Image (Does_File_Exist ("\input.txt")));
end File_Exists;</lang> This example should work with any Ada 2005 compiler. <lang ada>with Ada.Text_IO; use Ada.Text_IO; with Ada.Directories; use Ada.Directories;
procedure File_Exists is
procedure Print_File_Exist (Name : String) is begin Put_Line ("Does " & Name & " exist? " & Boolean'Image (Exists (Name))); end Print_File_Exist; procedure Print_Dir_Exist (Name : String) is begin Put_Line ("Does directory " & Name & " exist? " & Boolean'Image (Exists (Name) and then Kind (Name) = Directory)); end Print_Dir_Exist;
begin
Print_File_Exist ("input.txt" ); Print_File_Exist ("/input.txt"); Print_Dir_Exist ("docs"); Print_Dir_Exist ("/docs");
end File_Exists;</lang>
Aikido
The stat
function returns a System.Stat
object for an existing file or directory, or null
if it can't be found.
<lang aikido>
function exists (filename) {
return stat (filename) != null
}
exists ("input.txt") exists ("/input.txt") exists ("docs") exists ("/docs")
</lang>
Applesoft BASIC
The error code for FILE NOT FOUND is 6. <lang ApplesoftBasic>100 F$ = "THAT FILE" 110 T$(0) = "DOES NOT EXIST." 120 T$(1) = "EXISTS." 130 GOSUB 200"FILE EXISTS? 140 PRINT F$; " "; T$(E) 150 END
200 REM FILE EXISTS? 210 REM TRY 220 ON ERR GOTO 300"CATCH 230 PRINT CHR$(4); "VERIFY "; F$ 240 POKE 216, 0 : REM ONERR OFF 250 E = 1 260 GOTO 350"END TRY 300 REM CATCH 310 E = PEEK(222) <> 6 320 POKE 216, 0 : REM ONERR OFF 330 IF E THEN RESUME : REM THROW 340 CALL - 3288 : REM RECOVER 350 REM END TRY 360 RETURN </lang>
AutoHotkey
AutoHotkey’s FileExist() function returns an attribute string (a subset of "RASHNDOCT") if a matching file or directory is found. The attribute string must be parsed for the letter D to determine whether the match is a directory or file.
Another option is AutoHotkey's IfExist/IfNotExist command
<lang autohotkey>; FileExist() function examples ShowFileExist("input.txt") ShowFileExist("\input.txt") ShowFolderExist("docs") ShowFolderExist("\docs")
- IfExist/IfNotExist command examples (from documentation)
IfExist, D:\
MsgBox, The drive exists.
IfExist, D:\Docs\*.txt
MsgBox, At least one .txt file exists.
IfNotExist, C:\Temp\FlagFile.txt
MsgBox, The target file does not exist.
Return
ShowFileExist(file) {
If (FileExist(file) && !InStr(FileExist(file), "D")) MsgBox, file: %file% exists. Else MsgBox, file: %file% does NOT exist. Return
}
ShowFolderExist(folder) {
If InStr(FileExist(folder), "D") MsgBox, folder: %folder% exists. Else MsgBox, folder: %folder% does NOT exist. Return
}</lang>
AWK
<lang awk>@load "filefuncs" BEGIN {
exists("input.txt") exists("/input.txt") exists("docs") exists("/docs")
}
function exists(name ,fd) {
if ( stat(name, fd) == -1) print name " doesn't exist" else print name " exists"
}</lang>
Getline method. Also works in a Windows environment. <lang AWK>BEGIN {
exists("input.txt") exists("\\input.txt") exists("docs") exists("\\docs") exit(0)
}
- Check if file or directory exists, even 0-length file.
- Return 0 if not exist, 1 if exist
function exists(file ,line, msg) {
if ( (getline line < file) == -1 ) { # "Permission denied" is for MS-Windows msg = (ERRNO ~ /Permission denied/ || ERRNO ~ /a directory/) ? "1" : "0" close(file) return msg } else { close(file) return 1 }
}</lang>
Check file only (no directories) <lang>gawk 'BEGINFILE{if (ERRNO) {print "Not exist."; exit} } {print "Exist."; exit}' input.txt</lang>
Axe
<lang axe>If GetCalc("appvINPUT")
Disp "EXISTS",i
Else
Disp "DOES NOT EXIST",i
End</lang>
BASIC
<lang qbasic> ON ERROR GOTO ohNo f$ = "input.txt" GOSUB opener f$ = "\input.txt" GOSUB opener
'can't directly check for directories, 'but can check for the NUL device in the desired dir f$ = "docs\nul" GOSUB opener f$ = "\docs\nul" GOSUB opener END
opener:
e$ = " found" OPEN f$ FOR INPUT AS 1 PRINT f$; e$ CLOSE RETURN
ohNo:
IF (53 = ERR) OR (76 = ERR) THEN e$ = " not" + e$ ELSE e$ = "Unknown error" END IF RESUME NEXT
</lang>
You can also check for a directory by trying to enter it.
<lang qbasic> ON ERROR GOTO ohNo d$ = "docs" CHDIR d$ d$ = "\docs" CHDIR d$ END
ohNo:
IF 76 = ERR THEN PRINT d$; " not found" ELSE PRINT "Unknown error" END IF RESUME NEXT
</lang>
Later versions of MS-compatible BASICs include the DIR$
keyword, which makes this pretty trivial.
<lang qbasic> f$ = "input.txt" GOSUB opener f$ = "\input.txt" GOSUB opener
'can't directly check for directories, 'but can check for the NUL device in the desired dir f$ = "docs\nul" GOSUB opener f$ = "\docs\nul" GOSUB opener END
opener:
d$ = DIR$(f$) IF LEN(d$) THEN PRINT f$; " found" ELSE PRINT f$; " not found" END IF RETURN
</lang>
Batch File
<lang dos>if exist input.txt echo The following file called input.txt exists. if exist \input.txt echo The following file called \input.txt exists. if exist docs echo The following directory called docs exists. if exist \docs\ echo The following directory called \docs\ exists.</lang>
BBC BASIC
<lang bbcbasic> test% = OPENIN("input.txt")
IF test% THEN CLOSE #test% PRINT "File input.txt exists" ENDIF test% = OPENIN("\input.txt") IF test% THEN CLOSE #test% PRINT "File \input.txt exists" ENDIF test% = OPENIN("docs\NUL") IF test% THEN CLOSE #test% PRINT "Directory docs exists" ENDIF test% = OPENIN("\docs\NUL") IF test% THEN CLOSE #test% PRINT "Directory \docs exists" ENDIF</lang>
C
<lang c>#include <sys/types.h>
- include <sys/stat.h>
- include <stdio.h>
- include <unistd.h>
/* Check for regular file. */ int check_reg(const char *path) { struct stat sb; return stat(path, &sb) == 0 && S_ISREG(sb.st_mode); }
/* Check for directory. */ int check_dir(const char *path) { struct stat sb; return stat(path, &sb) == 0 && S_ISDIR(sb.st_mode); }
int main() { printf("input.txt is a regular file? %s\n", check_reg("input.txt") ? "yes" : "no"); printf("docs is a directory? %s\n", check_dir("docs") ? "yes" : "no"); printf("/input.txt is a regular file? %s\n", check_reg("/input.txt") ? "yes" : "no"); printf("/docs is a directory? %s\n", check_dir("/docs") ? "yes" : "no"); return 0; }</lang>
C++
<lang cpp>#include "boost/filesystem.hpp"
- include <string>
- include <iostream>
void testfile(std::string name) {
boost::filesystem::path file(name); if (exists(file)) { if (is_directory(file)) std::cout << name << " is a directory.\n"; else std::cout << name << " is a non-directory file.\n"; } else std::cout << name << " does not exist.\n";
}
int main() {
testfile("input.txt"); testfile("docs"); testfile("/input.txt"); testfile("/docs");
}</lang>
C#
<lang csharp>using System.IO;
Console.WriteLine(File.Exists("input.txt")); Console.WriteLine(File.Exists("/input.txt")); Console.WriteLine(Directory.Exists("docs")); Console.WriteLine(Directory.Exists("/docs"));</lang>
CoffeeScript
<lang coffeescript> fs = require 'fs' path = require 'path'
root = path.resolve '/' current_dir = __dirname filename = 'input.txt' dirname = 'docs'
local_file = path.join current_dir, filename local_dir = path.join current_dir, dirname
root_file = path.join root, filename root_dir = path.join root, dirname
for p in [ local_file, local_dir, root_file, root_dir ] then do ( p ) ->
fs.exists p, ( p_exists ) -> unless p_exists console.log "#{ p } does not exist." else then fs.stat p, ( error, stat ) -> console.log "#{ p } exists and is a #{ if stat.isFile() then 'file' else then 'directory' }."
</lang>
Clojure
<lang clojure>
(map #(.exists (clojure.java.io/as-file %)) '("/input.txt" "/docs" "./input.txt" "./docs"))
</lang>
Common Lisp
probe-file returns nil if a file does not exist. directory returns nil if there are no files in a specified directory. <lang lisp>(if (probe-file (make-pathname :name "input.txt"))
(print "rel file exists"))
(if (probe-file (make-pathname :directory '(:absolute "") :name "input.txt"))
(print "abs file exists"))
(if (directory (make-pathname :directory '(:relative "docs")))
(print "rel directory exists") (print "rel directory is not known to exist"))
(if (directory (make-pathname :directory '(:absolute "docs")))
(print "abs directory exists") (print "abs directory is not known to exist"))</lang>
There is no standardized way to determine if an empty directory exists, as Common Lisp dates from before the notion of directories as a type of file was near-universal. CL-FAD provides many of the therefore-missing capabilities in a cross-implementation library.
<lang lisp>(if (cl-fad:directory-exists-p (make-pathname :directory '(:relative "docs")))
(print "rel directory exists") (print "rel directory does not exist"))</lang>
D
<lang d>import std.stdio, std.file, std.path;
void verify(in string name) {
if (name.exists()) writeln("'", name, "' exists"); else writeln("'", name, "' doesn't exist");
}
void main() {
// check in current working dir verify("input.txt"); verify("docs");
// check in root verify(dirSeparator ~ "input.txt"); verify(dirSeparator ~ "docs");
}</lang>
- Output:
'input.txt' doesn't exist 'docs' doesn't exist '\input.txt' doesn't exist '\docs' doesn't exist
DCL
<lang DCL>$ if f$search( "input.txt" ) .eqs. "" $ then $ write sys$output "input.txt not found" $ else $ write sys$output "input.txt found" $ endif $ if f$search( "docs.dir" ) .eqs. "" $ then $ write sys$output "directory docs not found" $ else $ write sys$output "directory docs found" $ endif $ if f$search( "[000000]input.txt" ) .eqs. "" $ then $ write sys$output "[000000]input.txt not found" $ else $ write sys$output "[000000]input.txt found" $ endif $ if f$search( "[000000]docs.dir" ) .eqs. "" $ then $ write sys$output "directory [000000]docs not found" $ else $ write sys$output "directory [000000]docs found" $ endif</lang>
- Output:
$ @check_that_file_exists input.txt found directory docs not found [000000]input.txt not found directory [000000]docs not found
Delphi
<lang Delphi>program EnsureFileExists;
{$APPTYPE CONSOLE}
uses
SysUtils;
begin
if FileExists('input.txt') then Writeln('File "input.txt" exists.') else Writeln('File "input.txt" does not exist.');
if FileExists('\input.txt') then Writeln('File "\input.txt" exists.') else Writeln('File "\input.txt" does not exist.');
if DirectoryExists('docs') then Writeln('Directory "docs" exists.') else Writeln('Directory "docs" does not exists.');
if DirectoryExists('\docs') then Writeln('Directory "\docs" exists.') else Writeln('Directory "\docs" does not exists.');
end.</lang>
E
<lang e>for file in [<file:input.txt>,
<file:///input.txt>] { require(file.exists(), fn { `$file is missing!` }) require(!file.isDirectory(), fn { `$file is a directory!` })
}
for file in [<file:docs>,
<file:///docs>] { require(file.exists(), fn { `$file is missing!` }) require(file.isDirectory(), fn { `$file is not a directory!` })
}</lang>
Elena
<lang elena>#import system.
- import system'io.
- import extensions.
- symbol program =
[
console writeLine:"""input.txt"" file ":("input.txt" file_path is &available iif:"exists":"not found"). console writeLine:"""\input.txt"" file ":("\input.txt" file_path is &available iif:"exists":"not found"). console writeLine:"""docs"" directory ":("docs" directory_path is &available iif:"exists":"not found"). console writeLine:"""\docs"" directory ":("\docs" directory_path is &available iif:"exists":"not found").
].</lang>
Elixir
<lang Elixir>File.regular?("input.txt") File.dir?("docs") File.regular?("/input.txt") File.dir?("/docs")</lang>
Emacs Lisp
<lang Lisp>(file-exists-p "input.txt") (file-directory-p "docs") (file-exists-p "/input.txt") (file-directory-p "/docs")</lang>
file-exists-p
is true on both files and directories. file-directory-p
is true only on directories. Both go through the file-name-handler-alist
"magic filenames" mechanism so can act on remote files. On MS-DOS generally both /
and \
work to specify the root directory.
Erlang
<lang erlang>#!/usr/bin/escript existence( true ) ->"exists"; existence( false ) ->"does not exist".
print_result(Type, Name, Flag) -> io:fwrite( "~s ~s ~s~n", [Type, Name, existence(Flag)] ).
main(_) ->
print_result( "File", "input.txt", filelib:is_regular("input.txt") ), print_result( "Directory", "docs", filelib:is_dir("docs") ), print_result( "File", "/input.txt", filelib:is_regular("/input.txt") ), print_result( "Directory", "/docs", filelib:is_dir("/docs") ).
</lang>
Euphoria
<lang euphoria>include file.e
procedure ensure_exists(sequence name)
object x sequence s x = dir(name) if sequence(x) then if find('d',x[1][D_ATTRIBUTES]) then s = "directory" else s = "file" end if printf(1,"%s %s exists.\n",{name,s}) else printf(1,"%s does not exist.\n",{name}) end if
end procedure
ensure_exists("input.txt") ensure_exists("docs") ensure_exists("/input.txt") ensure_exists("/docs")</lang>
F#
<lang fsharp>open System.IO File.Exists("input.txt") Directory.Exists("docs") File.Exists("/input.txt") Directory.Exists(@"\docs")</lang>
Factor
<lang factor>: print-exists? ( path -- )
[ write ": " write ] [ exists? "exists." "doesn't exist." ? print ] bi ;
{ "input.txt" "/input.txt" "docs" "/docs" } [ print-exists? ] each</lang>
Forth
<lang forth>: .exists ( str len -- ) 2dup file-status nip 0= if type ." exists" else type ." does not exist" then ;
s" input.txt" .exists
s" /input.txt" .exists
s" docs" .exists
s" /docs" .exists</lang>
Fortran
Cannot check for directories in Fortran <lang fortran>LOGICAL :: file_exists INQUIRE(FILE="input.txt", EXIST=file_exists) ! file_exists will be TRUE if the file
! exists and FALSE otherwise
INQUIRE(FILE="/input.txt", EXIST=file_exists)</lang>
Actually, f90,f95 are able to deal with directory staff:
<lang fortran>logical :: dir_e ! a trick to be sure docs is a dir inquire( file="./docs/.", exist=dir_e ) if ( dir_e ) then
write(*,*), "dir exists!"
else
! workaround: it calls an extern program... call system('mkdir docs')
end if</lang>
GAP
<lang gap>IsExistingFile("input.txt"); IsDirectoryPath("docs"); IsExistingFile("/input.txt"); IsDirectoryPath("/docs");</lang>
Go
<lang go>package main
import (
"fmt" "os"
)
func printStat(p string) {
switch i, err := os.Stat(p); { case err != nil: fmt.Println(err) case i.IsDir(): fmt.Println(p, "is a directory") default: fmt.Println(p, "is a file") }
}
func main() {
printStat("input.txt") printStat("/input.txt") printStat("docs") printStat("/docs")
}</lang>
Groovy
<lang groovy>println new File('input.txt').exists() println new File('/input.txt').exists() println new File('docs').exists() println new File('/docs').exists()</lang>
Haskell
<lang haskell>import System.IO import System.Directory
check :: (FilePath -> IO Bool) -> FilePath -> IO () check p s = do
result <- p s putStrLn $ s ++ if result then " does exist" else " does not exist"
main = do
check doesFileExist "input.txt" check doesDirectoryExist "docs" check doesFileExist "/input.txt" check doesDirectoryExist "/docs"</lang>
HicEst
<lang hicest> OPEN(FIle= 'input.txt', OLD, IOStat=ios, ERror=99)
OPEN(FIle='C:\input.txt', OLD, IOStat=ios, ERror=99)
! ... 99 WRITE(Messagebox='!') 'File does not exist. Error message ', ios </lang>
Icon and Unicon
Icon doesn't support 'stat'; however, information can be obtained by use of the system function to access command line. <lang Unicon>every dir := !["./","/"] do {
write("file ", f := dir || "input.txt", if stat(f) then " exists." else " doesn't exist.") write("directory ", f := dir || "docs", if stat(f) then " exists." else " doesn't exist.") }</lang>
Note: Icon and Unicon accept both / and \ for directory separators.
IDL
<lang idl> print, FILE_TEST('input.txt') print, FILE_TEST(PATH_SEP()+'input.txt') print, FILE_TEST('docs', /DIRECTORY) print, FILE_TEST(PATH_SEP()+'docs', /DIRECTORY)
</lang>
J
<lang j>require 'files' fexist 'input.txt' fexist '/input.txt' direxist=: 2 = ftype direxist 'docs' direxist '/docs'</lang>
Java
<lang java>import java.io.File; public class FileExistsTest {
public static boolean isFileExists(String filename) { boolean exists = new File(filename).exists(); return exists; } public static void test(String type, String filename) { System.out.println("The following " + type + " called " + filename + (isFileExists(filename) ? " exists." : " not exists.") ); } public static void main(String args[]) { test("file", "input.txt"); test("file", File.separator + "input.txt"); test("directory", "docs"); test("directory", File.separator + "docs" + File.separator); }
}</lang>
<lang java5>import java.nio.file.FileSystem; import java.nio.file.FileSystems; import java.nio.file.Files; public class FileExistsTest{
private static FileSystem defaultFS = FileSystems.getDefault(); public static boolean isFileExists(String filename){ return Files.exists(defaultFS.getPath(filename)); } public static void test(String type, String filename){ System.out.println("The following " + type + " called " + filename + (isFileExists(filename) ? " exists." : " not exists.") ); } public static void main(String args[]){ test("file", "input.txt"); test("file", defaultFS.getSeparator() + "input.txt"); test("directory", "docs"); test("directory", defaultFS.getSeparator() + "docs" + defaultFS.getSeparator()); }
}</lang> Non retarded version: <lang java5> import java.nio.file.Files; public class FileExistsTest{
public static void main(String args[]){ System.out.printf("input.txt - %s", new File("input.txt").exists()); }
</lang>
JavaScript
<lang javascript>var fso = new ActiveXObject("Scripting.FileSystemObject");
fso.FileExists('input.txt'); fso.FileExists('c:/input.txt'); fso.FolderExists('docs'); fso.FolderExists('c:/docs');</lang>
Julia
<lang julia>isfile("input.txt") isfile("/input.txt") isdir("docs") isdir("/docs")</lang>
LabVIEW
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Lasso
<lang Lasso>// local file file_exists('input.txt')
// local directory file_exists('docs')
// file in root file system (requires permissions at user OS level) file_exists('//input.txt')
// directory in root file system (requires permissions at user OS level) file_exists('//docs')</lang>
LFE
From the LFE REPL: <lang lisp> > (: filelib is_regular '"input.txt") false > (: filelib is_dir '"docs") false > (: filelib is_regular '"/input.txt") false > (: filelib is_dir '"/docs")) false </lang>
Liberty BASIC
<lang lb>'fileExists.bas - Show how to determine if a file exists dim info$(10,10) input "Type a file path (ie. c:\windows\somefile.txt)?"; fpath$ if fileExists(fpath$) then
print fpath$; " exists!"
else
print fpath$; " doesn't exist!"
end if end
'return a true if the file in fullPath$ exists, else return false function fileExists(fullPath$)
files pathOnly$(fullPath$), filenameOnly$(fullPath$), info$() fileExists = val(info$(0, 0)) > 0
end function
'return just the directory path from a full file path function pathOnly$(fullPath$)
pathOnly$ = fullPath$ while right$(pathOnly$, 1) <> "\" and pathOnly$ <> "" pathOnly$ = left$(pathOnly$, len(pathOnly$)-1) wend
end function
'return just the filename from a full file path function filenameOnly$(fullPath$)
pathLength = len(pathOnly$(fullPath$)) filenameOnly$ = right$(fullPath$, len(fullPath$)-pathLength)
end function</lang>
LiveCode
<lang LiveCode>there is a file "/input.txt" there is a file "input.txt" there is a folder "docs" there is a file "/docs/input.txt"</lang> LiveCode also allows setting a default folder for subsequent file commands. To check if a file exists in the doc folder <lang LiveCode>set the defaultFolder to "docs" there is a file "input.txt"</lang>
Logo
<lang logo>show file? "input.txt show file? "/input.txt show file? "docs show file? "/docs</lang> Alternatively, one can set a file prefix used for subsequent file commands. <lang logo>setprefix "/ show file? "input.txt</lang>
Lua
For directories, the following only works on platforms on which directories can be opened for reading like files. <lang lua>function output( s, b )
if b then print ( s, " does not exist." ) else print ( s, " does exist." ) end
end
output( "input.txt", io.open( "input.txt", "r" ) == nil ) output( "/input.txt", io.open( "/input.txt", "r" ) == nil ) output( "docs", io.open( "docs", "r" ) == nil ) output( "/docs", io.open( "/docs", "r" ) == nil )</lang>
The following more portable solution uses LuaFileSystem. <lang lua>require "lfs" for i, path in ipairs({"input.txt", "/input.txt", "docs", "/docs"}) do
local mode = lfs.attributes(path, "mode") if mode then print(path .. " exists and is a " .. mode .. ".") else print(path .. " does not exist.") end
end</lang>
Maple
<lang Maple>with(FileTools): Exists("input.txt"); Exists("docs") and IsDirectory("docs"); Exists("/input.txt"); Exists("/docs") and IsDirectory("/docs");</lang>
Mathematica / Wolfram Language
<lang Mathematica>wd = NotebookDirectory[]; FileExistsQ[wd <> "input.txt"] DirectoryQ[wd <> "docs"]
FileExistsQ["/" <> "input.txt"] DirectoryQ["/" <> "docs"]</lang>
MATLAB / Octave
<lang Matlab> exist('input.txt','file')
exist('/input.txt','file') exist('docs','dir') exist('/docs','dir')</lang>
MAXScript
<lang maxscript>-- Here doesFileExist "input.txt" (getDirectories "docs").count == 1 -- Root doesFileExist "\input.txt" (getDirectories "C:\docs").count == 1</lang>
Modula-3
<lang modula3>MODULE FileTest EXPORTS Main;
IMPORT IO, Fmt, FS, File, OSError, Pathname;
PROCEDURE FileExists(file: Pathname.T): BOOLEAN =
VAR status: File.Status; BEGIN TRY status := FS.Status(file); RETURN TRUE; EXCEPT | OSError.E => RETURN FALSE; END; END FileExists;
BEGIN
IO.Put(Fmt.Bool(FileExists("input.txt")) & "\n"); IO.Put(Fmt.Bool(FileExists("/input.txt")) & "\n"); IO.Put(Fmt.Bool(FileExists("docs/")) & "\n"); IO.Put(Fmt.Bool(FileExists("/docs")) & "\n");
END FileTest.</lang>
Nemerle
<lang Nemerle>using System.Console; using System.IO;
WriteLine(File.Exists("input.txt")); WriteLine(File.Exists("/input.txt")); WriteLine(Directory.Exists("docs")); WriteLine(Directory.Exists("/docs"));</lang>
NetRexx
<lang NetRexx>/* NetRexx */ options replace format comments java crossref symbols binary
runSample(arg) return
-- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . method isExistingFile(fn) public static returns boolean
ff = File(fn) fExists = ff.exists() & ff.isFile() return fExists
-- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . method isExistingDirectory(fn) public static returns boolean
ff = File(fn) fExists = ff.exists() & ff.isDirectory() return fExists
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method runSample(arg) private static
parse arg files if files = then files = 'input.txt F docs D /input.txt F /docs D' loop while files.length > 0 parse files fn ft files select case(ft.upper()) when 'F' then do if isExistingFile(fn) then ex = 'exists' else ex = 'does not exist' say 'File fn' ex end when 'D' then do if isExistingDirectory(fn) then ex = 'exists' else ex = 'does not exist' say 'Directory fn' ex end otherwise do if isExistingFile(fn) then ex = 'exists' else ex = 'does not exist' say 'File fn' ex end end end
return
</lang>
NewLISP
<lang NewLISP>(dolist (file '("input.txt" "/input.txt"))
(if (file? file true) (println "file " file " exists")))
(dolist (dir '("docs" "/docs"))
(if (directory? dir) (println "directory " dir " exists")))</lang>
Nim
<lang nim>import os
echo existsFile "input.txt" echo existsFile "/input.txt" echo existsDir "docs" echo existsDir "/docs"</lang>
Objective-C
<lang objc>NSFileManager *fm = [NSFileManager defaultManager]; NSLog(@"input.txt %s", [fm fileExistsAtPath:@"input.txt"] ? @"exists" : @"doesn't exist"); NSLog(@"docs %s", [fm fileExistsAtPath:@"docs"] ? @"exists" : @"doesn't exist");</lang>
Objeck
<lang objeck> use IO;
bundle Default {
class Test { function : Main(args : String[]) ~ Nil { File->Exists("input.txt")->PrintLine(); File->Exists("/input.txt")->PrintLine(); Directory->Exists("docs")->PrintLine(); Directory->Exists("/docs")->PrintLine(); }
} </lang>
OCaml
<lang ocaml>Sys.file_exists "input.txt";; Sys.file_exists "docs";; Sys.file_exists "/input.txt";; Sys.file_exists "/docs";;</lang>
ooRexx
<lang oorexx>/**********************************************************************
- exists(filespec)
- returns 1 if filespec identifies a file with size>0
- (a file of size 0 is deemed not to exist.)
- or a directory
- 0 otherwise
- 09.06.2013 Walter Pachl (retrieved from my toolset)
- /
exists:
parse arg spec call sysfiletree spec, 'LIST', 'BL' if list.0\=1 then return 0 -- does not exist parse var list.1 . . size flags . if size>0 then return 1 -- real file If substr(flags,2,1)='D' Then Do Say spec 'is a directory' Return 1 End If size=0 Then Say spec 'is a zero-size file' Return 0</lang>
Oz
<lang oz>declare
[Path] = {Module.link ['x-oz://system/os/Path.ozf']}
in
{Show {Path.exists "docs"}} {Show {Path.exists "input.txt"}} {Show {Path.exists "/docs"}} {Show {Path.exists "/input.txt"}}</lang>
PARI/GP
<lang parigp>trap(,"does not exist",read("input.txt");"exists") trap(,"does not exist",read("c:\\input.txt");"exists") trap(,"does not exist",read("c:\\dirname\\nul");"exists")</lang>
A better version would use externstr
.
Under PARI it would typically be more convenient to use C methods.
Pascal
See Delphi
Phix
<lang Phix>constant fd = {"file","directory"}
procedure check(string name) object d = dir(name)
if sequence(d) then d = (find('d',d[1][D_ATTRIBUTES])!=0) printf(1,"%s %s exists.\n",{fd[1+d],name}) else printf(1,"%s does not exist.\n",{name}) end if
end procedure
check("input.txt") check("docs") check("/input.txt") check("/docs") check("/pagefile.sys") check("/Program Files (x86)")</lang>
- Output:
input.txt does not exist. directory docs exists. /input.txt does not exist. /docs does not exist. file /pagefile.sys exists. directory /Program Files (x86) exists.
PHP
<lang php>if (file_exists('input.txt')) echo 'input.txt is here right by my side'; if (file_exists('docs' )) echo 'docs is here with me'; if (file_exists('/input.txt')) echo 'input.txt is over there in the root dir'; if (file_exists('/docs' )) echo 'docs is over there in the root dir';</lang>
Perl
<lang perl>use File::Spec::Functions qw(catfile rootdir);
- here
print -e 'input.txt'; print -d 'docs';
- root dir
print -e catfile rootdir, 'input.txt'; print -d catfile rootdir, 'docs';</lang>
Without a Perl Module
A 1 is printed if the file or dir exists.
perl -e 'print -e "./input.txt", "\n";' perl -e 'print -d "./docs", "\n";' perl -e 'print -e "/input.txt", "\n";' perl -e 'print -d "/docs", "\n";'
Perl 6
<lang perl6>'input.txt'.IO ~~ :e; 'docs'.IO ~~ :d; '/input.txt'.IO ~~ :e; '/docs'.IO ~~ :d</lang>
PicoLisp
<lang PicoLisp>(if (info "file.txt")
(prinl "Size: " (car @) " bytes, last modified " (stamp (cadr @) (cddr @))) (prinl "File doesn't exist") )</lang>
Pike
<lang pike>import Stdio;
int main(){
if(exist("/var")){ write("/var exists!\n"); }
if(exist("file-exists.pike")){ write("I exist!\n"); }
}</lang>
PL/I
<lang pli>*Process source or(!);
/********************************************************************* * 20.10.2013 Walter Pachl * 'set dd:f=d:\_l\xxx.txt,recsize(300)' * 'tex' *********************************************************************/ tex: Proc Options(main); Dcl fid Char(30) Var Init('D:\_l\tst.txt'); Dcl xxx Char(30) Var Init('D:\_l\nix.txt'); Dcl r Char(1000) Var; Dcl f Record input; On Undefinedfile(f) Goto label; Open File(f) Title('/'!!fid); Read file(f) Into(r); Put Skip List('First line of file '!!fid!!': '!!r); Close File(f); Open File(f) Title('/'!!xxx); Read file(f) Into(r); Put Skip List(r); Close File(f); Label: Put Skip List('File '!!xxx!!' not found'); End;</lang>
- Output:
First line of file D:\_l\tst.txt: Test line 1 File D:\_l\nix.txt not found
Pop11
<lang pop11>sys_file_exists('input.txt') => sys_file_exists('/input.txt') => sys_file_exists('docs') => sys_file_exists('/docs') =></lang>
Note that the above literally checks for existence. Namely sys_file_exists returns true if file exists but can not be read.
The only sure method to check if file can be read is to try to open it. If one just wants to check if file is readable the following may be useful:
<lang pop11>;;; Define an auxilary function, returns boolean define file_readable(fname);
lvars f = sysopen(fname, 0, true, `A`); if f then sysclose(f); return (true); else return (false); endif;
enddefine;</lang>
The above works but is not the only way or the best way to check status of a file in Pop11. There is a very general procedure sys_file_stat that allows interrogation of a file or directory. The full documentation can be seen in the online documentation (search for sys_file_stat):
http://wwwcgi.rdg.ac.uk:8081/cgi-bin/cgiwrap/wsi14/poplog/pop11/ref/sysio
http://www.poplog.org/docs/popdocs/pop11/ref/sysio
http://www.cs.bham.ac.uk/research/projects/poplog/doc/popref/sysio (Not so well formatted).
Users can easily define special cases of the general procedure.
PowerShell
<lang powershell> Test-Path input.txt</lang>
Prolog
<lang prolog>
exists_file('input.txt'), exists_directory('docs').
exits_file('/input.txt'), exists_directory('/docs').
</lang>
PureBasic
<lang PureBasic>result = ReadFile(#PB_Any, "input.txt") If result>0 : Debug "this local file exists"
Else : Debug "result=" +Str(result) +" so this local file is missing"
EndIf
result = ReadFile(#PB_Any, "/input.txt") If result>0 : Debug "this root file exists"
Else : Debug "result=" +Str(result) +" so this root file is missing"
EndIf
result = ExamineDirectory(#PB_Any,"docs","") If result>0 : Debug "this local directory exists"
Else : Debug "result=" +Str(result) +" so this local directory is missing"
EndIf
result = ExamineDirectory(#PB_Any,"/docs","") If result>0 : Debug "this root directory exists"
Else : Debug "result=" +Str(result) +" so this root directory is missing"
EndIf </lang>
Python
The os.path.exists method will return True if a path exists False if it does not.
<lang python>import os
os.path.exists("input.txt") os.path.exists("/input.txt") os.path.exists("docs") os.path.exists("/docs")</lang>
R
<lang R>file.exists("input.txt") file.exists("/input.txt") file.exists("docs") file.exists("/docs")
- or
file.exists("input.txt", "/input.txt", "docs", "/docs")</lang>
The function file.exists returns a logical value (or a vector of logical values if more than one argument is passed)
Racket
<lang Racket>
- lang racket
- here
(file-exists? "input.txt") (file-exists? "docs")
- in the root
(file-exists? "/input.txt") (file-exists? "/docs")
- or in the root with relative paths
(parameterize ([current-directory "/"])
(and (file-exists? "input.txt") (file-exists? "docs")))
</lang>
Raven
<lang raven>'input.txt' exists if 'input.txt exists' print '/input.txt' exists if '/input.txt exists' print 'docs' isdir if 'docs exists and is a directory' print '/docs' isdir if '/docs exists and is a directory' print</lang>
REBOL
<lang REBOL>exists? %input.txt exists? %docs/
exists? %/input.txt exists? %/docs/</lang>
REXX
version 1
<lang rexx>/*REXX pgm creates a new empty file and directory; in curr dir and root.*/ fn='input.txt' dn='docs' @.1='current directory'; @.2='root directory' /*msgs for each pass.*/ parse upper version v; regina=pos('REGINA',v)\==0 /*Regina being used? */
do j=1 for 2; say /*perform these statements twice.*/ if stream(fn,'C',"QUERY EXISTS")== then say 'file ' fn " doesn't exist in the" @.j else say 'file ' fn " does exist in the" @.j if dosisdir(dn) then say 'directory ' dn " does exist in the" @.j else say 'directory ' dn " doesn't exist in the" @.j if regina then call chdir '\' /*use Regina's version of CHDIR.*/ else call doschdir '\' /*PC/REXX & Personal REXX version*/ end /*j*/ /*now, go and perform them again.*/ /*stick a fork in it, we're done.*/</lang>
version 2
<lang rexx> /* Check if a file already exists */ filename='file.txt' IF ~Openfile(filename) THEN CALL Openfile(':'filename) EXIT 0 Openfile: IF ~Exists(filename) THEN RETURN 0 CALL Open(filehandle,filename,'APPEND') RETURN 1 </lang>
RLaB
RLaB provides two user functions for the task, isfile and isdir. <lang RLaB> >> isdir("docs")
0
>> isfile("input.txt")
0
</lang>
Ruby
File.exists?
only checks if a file exists; it can be a regular file, a directory, or something else. File.file?
or File.directory?
checks for a regular file or a directory. Ruby also allows FileTest.file?
or FileTest.directory?
.
<lang ruby>File.file?("input.txt") File.file?("/input.txt") File.directory?("docs") File.directory?("/docs")</lang>
The next program runs all four checks and prints the results.
<lang ruby>["input.txt", "/input.txt"].each { |f|
printf "%s is a regular file? %s\n", f, File.file?(f) }
["docs", "/docs"].each { |d|
printf "%s is a directory? %s\n", d, File.directory?(d) }</lang>
Run BASIC
<lang runbasic>files #f,"input.txt" if #f hasanswer() = 1 then print "File does not exist"
files #f,"docs" if #f hasanswer() = 1 then print "File does not exist" if #f isDir() = 0 then print "This is a directory" </lang>
Scala
<lang scala>import java.nio.file.{ Files, FileSystems }
object FileExistsTest extends App {
val defaultFS = FileSystems.getDefault() val separator = defaultFS.getSeparator()
def test(filename: String) { val path = defaultFS.getPath(filename)
println(s"The following ${if (Files.isDirectory(path)) "directory" else "file"} called $filename" + (if (Files.exists(path)) " exists." else " not exists.")) }
// main List("output.txt", separator + "output.txt", "docs", separator + "docs" + separator).foreach(test)
}</lang>
Scheme
<lang scheme>(file-exists? filename)</lang>
Seed7
<lang seed7>$ include "seed7_05.s7i";
const proc: main is func
begin writeln(fileType("input.txt") = FILE_REGULAR); writeln(fileType("/input.txt") = FILE_REGULAR); writeln(fileType("docs") = FILE_DIR); writeln(fileType("/docs") = FILE_DIR); end func;</lang>
Sidef
<lang ruby># Here say (Dir.cwd + %f'input.txt' -> is_file); say (Dir.cwd + %d'docs' -> is_dir);
- Root
say (Dir.root + %f'input.txt' -> is_file); say (Dir.root + %d'docs' -> is_dir);</lang> NOTE: To check only for existence, use the method exists
Slate
<lang slate>(File newNamed: 'input.txt') exists (File newNamed: '/input.txt') exists (Directory root / 'input.txt') exists (Directory newNamed: 'docs') exists (Directory newNamed: '/docs') exists</lang>
Smalltalk
Squeak has no notion of 'current directory' because it isn't tied to the shell that created it.
<lang smalltalk>FileDirectory new fileExists: 'c:\serial'. (FileDirectory on: 'c:\') directoryExists: 'docs'.</lang>
In GNU Smalltalk instead you can do:
<lang smalltalk>(Directory name: 'docs') exists ifTrue: [ ... ] (Directory name: 'c:\docs') exists ifTrue: [ ... ] (File name: 'serial') isFile ifTrue: [ ... ] (File name: 'c:\serial') isFile ifTrue: [ ... ]</lang>
Using exists in the third and fourth case will return true for directories too.
Standard ML
<lang sml>OS.FileSys.access ("input.txt", []); OS.FileSys.access ("docs", []); OS.FileSys.access ("/input.txt", []); OS.FileSys.access ("/docs", []);</lang>
Tcl
Taking the meaning of the task from the DOS example: <lang tcl>if { [file exists "input.txt"] } {
puts "input.txt exists"
}
if { [file exists [file nativename "/input.txt"]] } {
puts "/input.txt exists"
}
if { [file isdirectory "docs"] } {
puts "docs exists and is a directory"
}
if { [file isdirectory [file nativename "/docs"]] } {
puts "/docs exists and is a directory"
}</lang> Note that these operations do not require the use of file nativename on either Windows or any version of Unix.
Toka
<lang toka>[ "R" file.open dup 0 <> [ dup file.close ] ifTrue 0 <> ] is exists? " input.txt" exists? . " /input.txt" exists? . " docs" exists? . " /docs" exists? .</lang>
TUSCRIPT
<lang tuscript> $$ MODE TUSCRIPT file="input.txt",directory="docs" IF (file=='file') THEN PRINT file, " exists" ELSE PRINT/ERROR file," not exists" ENDIF IF (directory=='project') THEN PRINT directory," exists" ELSE PRINT/ERROR "directory ",directory," not exists" ENDIF </lang>
- Output:
input.txt exists @@@@@@@@ directory docs not exists @@@@@@@@
UNIX Shell
<lang bash>test -f input.txt test -f /input.txt test -d docs test -d /docs</lang>
The next program runs all four checks and prints the results.
<lang bash>for f in input.txt /input.txt; do test -f "$f" && r=true || r=false echo "$f is a regular file? $r" done for d in docs /docs; do test -d "$d" && r=true || r=false echo "$d is a directory? $r" done</lang>
Vedit macro language
Vedit allows using either '\' or '/' as directory separator character, it is automatically converted to the one used by the operating system. <lang vedit>// In current directory if (File_Exist("input.txt")) { M("input.txt exists\n") } else { M("input.txt does not exist\n") } if (File_Exist("docs/nul", NOERR)) { M("docs exists\n") } else { M("docs does not exist\n") }
// In the root directory if (File_Exist("/input.txt")) { M("/input.txt exists\n") } else { M("/input.txt does not exist\n") } if (File_Exist("/docs/nul", NOERR)) { M("/docs exists\n") } else { M("/docs does not exist\n") }</lang>
Visual Basic .NET
Platform: .NET
<lang vbnet>'Current Directory Console.WriteLine(If(IO.Directory.Exists("docs"), "directory exists", "directory doesn't exists")) Console.WriteLine(If(IO.Directory.Exists("output.txt"), "file exists", "file doesn't exists"))
'Root Console.WriteLine(If(IO.Directory.Exists("\docs"), "directory exists", "directory doesn't exists")) Console.WriteLine(If(IO.Directory.Exists("\output.txt"), "file exists", "file doesn't exists"))
'Root, platform independent Console.WriteLine(If(IO.Directory.Exists(IO.Path.DirectorySeparatorChar & "docs"), _
"directory exists", "directory doesn't exists"))
Console.WriteLine(If(IO.Directory.Exists(IO.Path.DirectorySeparatorChar & "output.txt"), _
"file exists", "file doesn't exists"))</lang>
VBScript
<lang vbscript>Set FSO=CreateObject("Scripting.FileSystemObject") Function FileExists(strFile) if FSO.fileExists(strFile) then FileExists=true else FileExists=false end if end function
Function folderExists(strFolder) if FSO.folderExists(strFolder) then folderExists=true else folderexists=false end if end function
usage (apostrophes indicate comments-this section will not be run) 'if fileExists("C:\test.txt") then 'msgbox"It Exists!" 'else 'msgbox"awww" 'end if ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' </lang>
zkl
<lang zkl>File.exists("input.txt") //--> True (in this case a sym link) File.exists("/input.txt") //-->False File.isDir("/") //-->True File.isDir("docs") //-->False </lang>
- Programming Tasks
- File System Operations
- Simple
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