Batch - Read contents of a file in an array

Question

I've a text file with two rows (say param.txt) which is shown below:

Mar2012
dim1,dim2,dim3,dim4

I want to read this file in batch and store the contents of first line in a variable called cube_name. When I'm reading the second line, I want to split the comma delimited string dim1,dim2,dim3,dim4 and create an array of four elements. I am planning to use the variable and the array in later part of the script.

The code which I created is shown below. The code is not working as expected.

@echo off & setlocal enableextensions enabledelayedexpansion
set /a count_=0
for /f "tokens=*" %%a in ('type param.txt') do (
set /a count_+=1
set my_arr[!count_!]=%%a
)
set /a count=0
for %%i in (%my_arr%) do (
set /a count+=1
if !count! EQU 1 (
    set cube_name=%%i
)

if !count! GTR 1 (
    set dim_arr=%%i:@=,%
)
)
for %%i in (%dim_arr%) do (
echo %%i
)

echo !cube_name!

I get to see the following when I run the code:

C:\Working folder>test2.bat
ECHO is off.

So this doesn't appear to work and I can't figure out what I'm doing wrong. I am fairly new to the batch scripting so help is appreciated

dbenham · Accepted Answer · 2012-04-17T18:01:59.533

Your first FOR loop is OK. It is not how I would do it, but it works. Everything after that is a mess. It looks like you think arrays are a formal concept in batch, when they are not. It is possible to work with variables in a way that looks reminiscent of arrays. But true arrays do not exist within batch.

You use %my_arr% as if it is an array, but my_arr is not even defined. You have defined variables my_arr[1] amd my_arr[2] - the brackets and number are part of the variable name.

It also looks like you have a misunderstanding of FOR loops. I suggest you carefully read the FOR documentation (type HELP FOR from a command line). Also look at examples on this and other sites. The FOR command is very complicated because it has many variations that look similar to the untrained eye, yet have profoundly different behaviors. One excellent resource to help your understanding is http://judago.webs.com/batchforloops.htm

Assuming the file always has exactly 2 lines, I would solve your problem like so

@echo off
setlocal enableDelayedExpansion
set dimCnt=0
<param.txt (
  set /p "cube_name=" >nul
  set /p "dimList=" >nul
  for %%D in (!dimList!) do (
    set /a dimCnt+=1
    set "dim[!dimCnt!]=%%D"
  )
)
echo cube_name=!cube_name!
  for /l %%I in (1 1 !dimCnt!) do echo dim[%%I]=!dim[%%I]!

One nice feature of the above solution is it allows for a varying number of terms in the list of dimensions in the 2nd line. It will fail if there are tabs, spaces, semicolon, equal, * or ? in the dimension names. There are relatively simple ways to get around this limitation if need be.

Tabs, spaces, semicolon and equal can be handled by using search and replace to enclose each term in quotes.

  for %%D in ("!dimList:,=","!") do (
    set /a dimCnt+=1
    set "dim[!dimCnt!]=%%~D"
  )

I won't post the full solution here since it is not likely to be needed. But handling * and/or ? would require replacing the commas with a new-line character and switching to a FOR /F statement.

score 1 · Answer 2 · answered Apr 17 '12 at 17:00

I'm impressed of your code!
Do you try to debug or echo anything there?

You could simply add some echo's to see why your code can't work.

@echo off & setlocal enableextensions enabledelayedexpansion
set /a count_=0
for /f "tokens=*" %%a in ('type param.txt') do (
  set /a count_+=1
  set my_arr[!count_!]=%%a
)
echo ### show the variable(s) beginning with my_arr...
set my_arr

echo Part 2----
set /a count=0
echo The value of my_arr is "%my_arr%"
for %%i in (%my_arr%) do (
    set /a count+=1
    echo ## Count=!count!, content is %%i
    if !count! EQU 1 (
        set cube_name=%%i
    )

    if !count! GTR 1 (
        echo ## Setting dim_arr to "%%i:@=,%"
        set dim_arr=%%i:@=,%
        echo 
    )
)
for %%i in (%dim_arr%) do (
    echo the value of dim_arr is "%%i"
)

echo cube_name is "!cube_name!"

Output is

### show the variable(s) beginning with my_arr...
my_arr[1]=Mar2012
my_arr[2]=dim1,dim2,dim3,dim4
Part 2----
The value of my_arr is ""
cube_name is ""

As you can see your part2 fails completly.

Batch - Read contents of a file in an array

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