Reading a file: checking to see if a file exists.

[Bege]

Does anyone know what the code is to check if a file exists?

Ex: If the user was asked to enter the name of a file to load, then the program could check if the file exists. Then the program wouldn't crash when the user enters a file name which does not exist, but rather just tell the user that that file does not exist.

[Mazer]

File.Exists (pathName : string) : boolean

it's a function that takes a path name for a file and returns true or false depending on whether or not the file exists.

eg

code:

var filename : string get filename if File.Exists (filename) then     put "So, there you go." end if

well, that should do it.

[Tony]

well you could use assert, but I think that will terminate the program.

when you open the file, the pointer to it is assigned a possitive integer. If that variable is 0 or a negative, it means file was not opened so you should display an appropriate message.

code:

var file:int open : file, "test.txt", get if file <=0 then put "file not found" end if

[Bege]

Thanks, apreciate it very much.

[Mazer]

yeah, assert is pretty stinking useless, i don't know why people ever used it in programs.

[junkpro11]

i used File.Exist cuz i found it in the turing reference but when i use it in my program it doesnt detect the file exist

this is my code for file.exists

code:

var sname:string loop get sname if File.Exists (sname) then Music.Play ("a") end if exit when File.Exists (sname)=true end loop

[s_climax]

It works for me, but only if my filename has one word only in the title.

[junkpro11]

i put the checking of file exists in a loop
and even when the file exist it doesnt exit......so weird

is my code correct though?

[guruguru]

Yours worked for me... so did mine 8) . Remember to add the extension (eg. unamed.txt). And make sure its in the same folder me thinks.

code:

var sname : string loop     get sname     if File.Exists (sname) then         Music.Play ("a")         exit     end if end loop put "Got it!"

[beard0]

s_climax wrote:

It works for me, but only if my filename has one word only in the title.

To allow for sname with spaces, must use:

get sname : *

this gets everything up to enter as opposed to everything up to white space.

[junkpro11]

Quote:

Yours worked for me... so did mine 8) . Remember to add the extension (eg. unamed.txt). And make sure its in the same folder me thinks.

where do i add the .t extensions? i tried adding in bracket it didnt work...and when i tried (sname)+".t" it doesnt allow me to do that

so if i want to see if (sname) .t file exist wat do i do???

[beard0]

This should work for you junkpro11:

code:

var sname:string loop     get sname     if File.Exists (sname) or File.Exists(sname+".t") then         Music.Play ("a")         exit     end if end loop

Note:
the =true on your exit statement is uneccesary. Whenever you hav a condition, it's checking to see if it's true. You don't need to tell it that. Also, your exit condition is the same as your if condition - just put "exit" in your if condition.

[junkpro11]

my teacher wants onli "exit when" 's in loop, no double exits and no just "exit"

[SuperGenius]

junkpro11 wrote:

my teacher wants onli "exit when" 's in loop, no double exits and no just "exit"

that is stupid, as sometimes you don't need a condition. Some teachers should get bent.

[guruguru]

Well there is always condition. The exit is always in an if statment. But I agree its stupid .

code:

var sname:string loop     get sname     exit when File.Exists (sname) or File.Exists(sname+".t") end loop

Or if you want the sound... it gets worse...

code:

var sname:string loop     get sname     if File.Exists (sname) or File.Exists(sname+".t") then         Music.Play ("a")     end if     exit when File.Exists (sname) or File.Exists(sname+".t") end loop