Check that file exists: Difference between revisions

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=={{header|C++}}==

<lang cpp>#include "boost/filesystem.hpp"

#include "boost/filesystem.hpp"

#include <string>

#include <iostream>

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testfile("/input.txt");

testfile("/docs");

⚫

}</lang>

}

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</lang>

=={{header|C sharp|C#}}==

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=={{header|Clojure}}==

⚫

<lang lisp>(import '(java.io File))

⚫

(import '(java.io File))

(defn kind [filename]

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(look-for "/input.txt")

(look-for "docs")

(look-for "/docs")

(look-for "/docs")</lang>

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</lang>

=={{header|Common Lisp}}==

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=={{header|D}}==

<lang d>import std.file, std.path: sep;

import std.file, std.path: sep;

void verify(string name) {

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// check in root

verify(sep~"input.txt"); verify(sep~"docs");

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}</lang>

}

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</lang>

=={{header|DOS Batch File}}==

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=={{header|E}}==

for file in [<file:input.txt>,

<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!` })

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}</lang>

}

=={{header|Forth}}==

: .exists ( str len -- ) 2dup file-status nip 0= if type ." exists" else type ." does not exist" then ;

<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

s" /docs" .exists</lang>

=={{header|Fortran}}==

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Cannot check for directories in Fortran

<lang fortran> LOGICAL :: file_exists

<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

<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>

=={{header|Haskell}}==

import System.IO

<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"

check doesDirectoryExist "/docs"</lang>

=={{header|J}}==

<lang j> require 'files'

<lang j>require 'files'

fexist 'input.txt'

fexist '/input.txt'

direxist=: 2 = ftype

direxist 'docs'

direxist '/docs'</lang>

=={{header|Java}}==

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=={{header|Logo}}==

<lang logo>show file? "input.txt

⚫

show file? "input.txt

show file? "/input.txt

show file? "docs

show file? "/docs

show file? "/docs</lang>

</lang>

Alternatively, one can set a file prefix used for subsequent file commands.

<lang logo>setprefix "/

⚫

show file? "input.txt</lang>

setprefix "/

show file? "input.txt

</lang>

=={{header|MAXScript}}==

-- Here

<lang maxscript>-- Here

doesFileExist "input.txt"

(getDirectories "docs").count == 1

-- Root

doesFileExist "\input.txt"

(getDirectories "C:\docs").count == 1

(getDirectories "C:\docs").count == 1</lang>

=={{header|Modula-3}}==

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=={{header|Pop11}}==

sys_file_exists('input.txt') =>

<lang pop11>sys_file_exists('input.txt') =>

sys_file_exists('/input.txt') =>

sys_file_exists('docs') =>

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.

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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:

;;; Define an auxilary function, returns boolean

<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;

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):

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=={{header|Raven}}==

<lang raven> 'input.txt' exists if 'input.txt exists' print

<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>

=={{header|Ruby}}==

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=={{header|Slate}}==

<lang slate>(File newNamed: 'input.txt') exists

(File newNamed: 'input.txt') exists

(File newNamed: '/input.txt') exists

(Directory root / 'input.txt') exists

(Directory newNamed: 'docs') exists

(Directory newNamed: '/docs') exists

(Directory newNamed: '/docs') exists</lang>

</lang>

=={{header|Smalltalk}}==

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[[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'.

<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: [ ... ]

<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.

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=={{header|Toka}}==

[ "R" file.open dup 0 <> [ dup file.close ] ifTrue 0 <> ] is exists?

<lang toka>[ "R" file.open dup 0 <> [ dup file.close ] ifTrue 0 <> ] is exists?

" input.txt" exists? .

" /input.txt" exists? .

" docs" exists? .

" /docs" exists? .

" /docs" exists? .</lang>

=={{header|UNIX Shell}}==

test -f input.txt

<lang bash>test -f input.txt

test -f /input.txt

test -d docs

test -d /docs

test -d /docs</lang>

=={{header|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

// 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") }

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// 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") }

if (File_Exist("/docs/nul", NOERR)) { M("/docs exists\n") } else { M("/docs does not exist\n") }</lang>

</lang>

=={{header|Visual Basic .NET}}==

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'Current Directory

<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"))

"file exists", "file doesn't exists"))</lang>

{{omit from|TI-83 BASIC}} {{omit from|TI-89 BASIC}}