Arrays in Batch Scripting Language

Array in Batch language
Test the existance of an element
Iterate through the elements of the array
An element has stucture

1. Array in Batch language

An array is a row of contiguous elements which are marked indices: 0, 1, 2, ....

For other languages an array has fixed size. But in the Batch language, the array has a dynamic size, and there is no attribute describing array length (the number of array elements). And no function directly helps you get the number of array elements.

All array elements need to be assigned values through a set command. If not, such element doesn't exist .

@echo off
set myarray[0] = Abc
set /A myarray[1] = 234
set myarray[2]=Def

set myarray[0]=A new value

Example:

arrayExample1.bat

@echo off
set names[0]=Tom
set names[1]=Jerry
set names[2]=Donald
set names[3]=Aladin

echo names[0]= %names[0]%
echo names[3]= %names[3]%

@rem names[10] does not exists!
echo names[10]= %names[10]%
pause

You can assign new values to array elements. Below is an example:

arrayExample2.bat

@echo off
set names[0]=Tom
set names[1]=Jerry
echo names[0]= %names[0]%

@rem: Assign new value
set names[0]=Donald

echo After assign new value to names[0]:
echo names[0]= %names[0]%
pause

2. Test the existance of an element

Using defined command helps you to check whether an element in an array exists or not?

arrayDefinedExample.bat

@echo off
set Arr[0]=1000
set Arr[1]=5000
set Arr[2]=3000

if not defined Arr[5] (
   echo Element at 5 does not exists!
)
if defined Arr[1] (
   echo Element at 1 exists!
)
pause

3. Iterate through the elements of the array

See more:
Batch Loops

For /F loop can be approved on a range of numbers, therefore, it can be approved on a range of array indices

fetchArrayExample1.bat

@echo off
set fruits[0]=Apple
set fruits[1]=Apricot
set fruits[2]=Asparagus
set fruits[3]=Aubergine
set fruits[4]=Banana

FOR /L %%i IN (0 1 4) DO  (
   call echo Element At %%i = %%fruits[%%i]%%
)
pause

If you don't know the number of array elements in advance, you can iterate over its elements by using goto command.

fetchArrayExample2.bat

@echo off
set fruits[0]=Apple
set fruits[1]=Apricot
set fruits[2]=Asparagus
set fruits[3]=Aubergine
set fruits[4]=Banana

set /A i = 0
:my_loop 
    if defined fruits[%i%]  (
        call echo Element At %i% = %%fruits[%i%]%%  
        set /a i = %i% + 1
        goto :my_loop
    ) 
echo Done!
pause

4. An element has stucture

In the Batch language, an array element can have structure. A structure is an object with many attributes, for example an object represents for a person with 2 attributes such as firstName, lastName.

structureArrayExample.bat

@echo off
set persons[0].firstName=Bill
set persons[0].lastName=Gates

set persons[1].firstName=Steve
set persons[1].lastName=Jobs

set persons[2].firstName=Mark
set persons[2].lastName=Zuckerberg 

set persons[3].firstName=Sundar
set persons[3].lastName=Pichai

FOR /L %%i IN (0 1 3) DO  (
   call echo Person At %%i = %%persons[%%i].firstName%% %%persons[%%i].lastName%%
)
pause