3. Batch File, How to declare Variables, Using FOR loops in batch file

How to declare a variable in batch file
Answer is to use set command.

Set command has 3 options
set     => Declares a string variable
set /a  => declares an integer variable
set /p  => Gets the input from the user

When you want to refer a variable use %var%. e..g
 

 ::Declaring a variable, declare a variable using set  
 ::remember not put spaces around "=" while assigning values to the variable  
 set var1=hello, World!  
 echo %var1%  
 set var2= This is NeoTheSaviour  
 echo %var1%%var2%  

How to declare integer variables

 ::When you set any variable by default its a string, as you have seen in above example  
 ::set has 2 other options, 1) /a which interprate given input as integer  
 set /a var1=10  
 set /a var2=5  
 set /a var3=%var1%+%var2%  
 echo Sum 0f %var1% and %var2% is %var3%  
 set /a var3=%var1%*%var2%  
 echo Product is %var3%  

Taking input from user

 ::second option set has to take input from User /p  
 echo Addition of Two numbers  
 set /p var1=Input First Integer   
 set /p var2=Input Second Integer   
 set /a var3=%var1%+%var2%  
 echo Sum is %var3%  

You can download above batch file from here


For Loops
Syntax is like below. Note that we use %% while referring iterator.

 ::For loops and variable  
 :: For loop uses iterator with %%  
 for %%a in (a b c d) do echo %%a  
 ::second way of for loop  
 FOR /L %%i IN (0,1,5) do (  
      echo %%i  
      )