Am I approaching this the right way ?

[cpt2400]

I have just started a little project with AutoIt. I have never used it before

and want to make sure I am not headed down the wrong path.

The script needs to compare two files. File 1 will be the standard, and File 2

will be compared to it. Any discrepencies to File 1 will be written to an error log.

I have tried to include some error checking as well.

A second point is the matter of arrays. The documentation says this ...

"An Array is a variable containing series of data elements of the same type and size.

Each element in this variable can be accessed by an index number.

Before you can start using Arrays in your script, you must define their bounds using the 'Dim' keyword. "

However, as you see in my code, while the Arrays are declared, they are not dimensioned.

And each element is holding a string of varying length.

Am I building something that is going to crash when I least expect it? Any comments will be appreciated.

CODE FOLLOWS

; Use this as the basis for the file comparision script

#include <file.au3>

$Er_File = FileOpen("C:/exp/File_Error_Log.txt", 1)

Dim $aFile

Dim $bFile

; Large arrays are no problem. I put 8904 lines in, in no time.

; Apparently, arrays do NOT have to be dimensioned before they are used.

; Write another script to see if they can be dynamically resized.

; Doesn't work, 1st array is 'deleted' then refilled

; I am using text files from Project Gutenberg to simulate

If Not _FileReadToArray("C:/exp/txt_01/DGrey.txt",$aFile) Then

FileWriteLine( $Er_File, "C:/exp/txt_01/DGrey.txt could not be loaded into the array. Script will exit.")

Exit

EndIf

If Not _FileReadToArray("C:/exp/txt_04/DGrey_bad.txt",$bFile) Then

FileWriteLine( $Er_File, "C:/exp/txt_04/DGrey_bad.txt could not be loaded into the array. Script will exit.")

Exit

EndIf

FileWriteLine( $Er_File, "C:/exp/txt_01/DGrey.txt is the Standard.")

FileWriteLine( $Er_File, "C:/exp/txt_04/DGrey_bad.txt is being compared to the Standard.")

FileWriteLine( $Er_File, " . . . . . . . . . . . . . . . . . . . . . . . . ")

FileWriteLine( $Er_File, " . . . . . . . . . . . . ")

If $aFile[0] > $bFile[0] Then

FileWriteLine( $Er_File, "C:/exp/txt_04/DGrey_bad.txt has less lines than the Test Standard and will not be checked.")

Exit

EndIf

If $aFile[0] < $bFile[0] Then

FileWriteLine( $Er_File, "C:/exp/txt_04/DGrey_bad.txt has more lines than the Test Standard and will not be checked.")

Exit

EndIf

For $x = 1 to $aFile[0]

If $aFile[$x] <> $bFile[$x] Then

FileWriteLine( $Er_File, "Line "& $x & " is different from the Standard.")

FileWriteLine( $Er_File, "The Standard is : "& $aFile[$x] )

FileWriteLine( $Er_File, "The file being checked is : "& $bFile[$x] )

FileWriteLine( $Er_File, " . . . . . . . . . . . . ")

EndIf

Next

FileClose( $Er_File )

MsgBox( 48, "Success", "How many records are there in 1st array : " & $aFile[0])

MsgBox( 48, "Success", "How many records are there in 2nd array : " & $bFile[0])

[martin]

...

However, as you see in my code, while the Arrays are declared, they are not dimensioned.

And each element is holding a string of varying length.

Am I building something that is going to crash when I least expect it? Any comments will be appreciated.

You must declare the variable with the number of elements or it is not an array. You can change the number of elements with ReDim and check the number of elements with UBound.

Your code might work because _FileReadToArray will simply convert the variable you pass ByRef into an array, so in this case you do not need to declare it as an array and a simple Dim, Local or Global declaration would be ok.

However, it might be wise to check that the variable is an array before you use it as one because _FileReadToioArray might fail. Something like

If IsArray($aFile) then

[cpt2400]

You must declare the variable with the number of elements or it is not an array. You can change the number of elements with ReDim and check the number of elements with UBound.

Your code might work because _FileReadToArray will simply convert the variable you pass ByRef into an array, so in this case you do not need to declare it as an array and a simple Dim, Local or Global declaration would be ok.

However, it might be wise to check that the variable is an array before you use it as one because _FileReadToioArray might fail. Something like

If IsArray($aFile) then

I did some more experimenting as you suggested. $aFile is NOT an array after it is declared, but it IS an array after calling _FileReadToArray.

The code I posted works fine. It takes a text file that has 8904 lines and puts each line into an array element. Then I compare the arrays and single out the lines that are different.

I looked at the function code for _FileReadToArray, and could not see how the array was loaded. As far as I can tell, there is no loop in the code.

And I am very curious as to why the arrays I declare are static, but the array inside _FileReadToArray is (or appears to be) dynamic?

Can anyone help?

[Melba23]

cpt2400,

$aFile is NOT an array after it is declared, but it IS an array after calling _FileReadToArray

This is because you have not declared $aFile with any dimensions. As martin pointed out, you must declare the size when you create an array. Just declaring the name merely declares a variable. In fact you can use this to destroy arrays which are no longer needed - from the Help file:

To erase an array (maybe because it is a large global array and you want to free the memory), simply assign a single value to it:

$array = 0. This will free the array and convert it back to the single value of 0.

I am very curious as to why the arrays I declare are static, but the array inside _FileReadToArray is (or appears to be) dynamic

AutoIt arrays are dynamic - as long as you ask them to be. Look at ReDim in the Help file. _FileListToArray uses this function to resize the returned array as required.

Incidentally, using Dim to declare an array is not recommended - unless you want to erase all the elements of an existing array. It is better practice to use Global/Local as with normal variables.

I hope that clears up the questions you had.

M23

[martin]

I did some more experimenting as you suggested. $aFile is NOT an array after it is declared, but it IS an array after calling _FileReadToArray.

Yes I know that, that is what I told you so I think you misunderstood. Please reread my post

The code I posted works fine. It takes a text file that has 8904 lines and puts each line into an array element. Then I compare the arrays and single out the lines that are different.

Again, as I said "Your code might work because _FileReadToArray will simply convert the variable you pass ByRef into an array,..."

The word "might" was used becuase it looked to me like it should work but I didn't try it.

I looked at the function code for _FileReadToArray, and could not see how the array was loaded. As far as I can tell, there is no loop in the code.

And I am very curious as to why the arrays I declare are static, but the array inside _FileReadToArray is (or appears to be) dynamic?

Can anyone help?

As said, the function _FileReadtoArray converts the variable to an array.

Suppose you have variable $a and $b

Global $a

$a = "bannanas"
$b = 987

ConsoleWrite("$a and $b = " & $a & ', ' & $b & @CRLF)
;will show what you expect.

ConsoleWrite("$a is an array? " & (IsArray($a)=True) & @CRLF)
;will show it is not an array, again as expected.

;Now make $a the return from a function which produces an array
$a = StringSplit("a,b,c,d,e,f",',')
ConsoleWrite("After assigning $a to stringsplit $a is an array? " & (IsArray($a) = True) & @CRLF)
for $n = 1 to $a[0]
 ConsoleWrite($a[$n] & @CRLF)
next

This is what happens in the function _FileToArray. Just study the function and you will see what happens, no loop is needed. You need to play around with arrays a bit more.

I don't really know what you mean by the variable you declare as being static. Since you declare in global space I would simply call it Global. My experience of static variables is in C where you can have a static variable declared in a function but which is retained in memory and the last value set is used the next time the function is called, but it is only available in that function. AutoIt does not have such a variable type and you would have to use a Global variable, or pass a variable using ByRef for example.

EDIT: AutoIt does have static variables as of Beta version 3.3.1.4 26th October 2009.

Edited November 7, 2009 by martin

[cpt2400]

Yes I know that, that is what I told you so I think you misunderstood. Please reread my post

Again, as I said "Your code might work because _FileReadToArray will simply convert the variable you pass ByRef into an array,..."

The word "might" was used becuase it looked to me like it should work but I didn't try it.

As said, the function _FileReadtoArray converts the variable to an array.

Suppose you have variable $a and $b

Global $a

$a = "bannanas"

$b = 987

ConsoleWrite("$a and $b = " & $a & ', ' & $b & @CRLF)

;will show what you expect.

ConsoleWrite("$a is an array? " & (IsArray($a)=True) & @CRLF)

;will show it is not an array, again as expected.

;Now make $a the return from a function which produces an array

$a = StringSplit("a,b,c,d,e,f",',')

ConsoleWrite("After assigning $a to stringsplit $a is an array? " & (IsArray($a) = True) & @CRLF)

for $n = 1 to $a[0]

ConsoleWrite($a[$n] & @CRLF)

next

[code=auto:0]

This is what happens in the function _FileToArray. Just study the function and you will see what happens, no loop is needed. You need to play around with arrays a bit more.

I don't really know what you mean by the variable you declare as being static. Since you declare in global space I would simply call it Global. My experience of static variables is in C where you can have a static variable declared in a function but which is retained in memory and the last value set is used the next time the function is called, but it is only available in that function. AutoIt does not have such a variable type and you would have to use a Global variable, or pass a variable using ByRef for example.

I want to thank everyone for helping me understand. I will spend more time studying the help file, and these replies. Just to clarify this last response, I was speaking of static arrays, not static variables.

Once again, thanks. And watch out, I think I have learned just enough to be dangerous.