## Wednesday, April 28, 2010

### [Batch File] Rediscovering CMD.EXE batch scripts

Insanity must be setting in; I’ve been trying to solve RosettaCode tasks with Windows CMD.EXE batch scripts. For example, their A+B task:

A+B - in programming contests, classic problem, which is given so contestants can gain familiarity with online judging system being used.

A+B is one of few problems on contests, which traditionally lacks fabula.

Problem statement Given 2 integer numbers, A and B. One needs to find their sum.

Input data
Two integer numbers are written in the input stream, separated by space.
Output data
The required output is one integer: the sum of A and B.
Example:

Input Output

2 2 4

3 2 5

These are what I posted as solutions:

Prompts version

```::aplusb.cmd
@echo off
setlocal
set /p a="A: "
set /p b="B: "
set /a c=a+b
echo %c%
endlocal```

All on the commandline version

```::aplusb.cmd
@echo off
setlocal
set a=%1
set b=%2
set /a c=a+b
echo %c%
endlocal```

Formula on the command line version

```::aplusb.cmd
@echo off
setlocal
set /a c=%~1
echo %c%
endlocal```

Example of 'Formula on the command line version'

```>aplusb 123+456
579
>aplusb "1+999"
1000```

Parse the input stream version (thanks to Tom Lavedas on alt.msdos.batch.nt)

```::aplusb.cmd
@echo off
setlocal
set /p a="Input stream: "
echo %res%
endlocal
goto :eof

set /a res=res+%1
shift
if "%1" neq "" goto :add```

Example of 'parse the input stream version'

```>aplusb
Input stream: 1234 5678
6912
>aplusb
Input stream: 123 234 345 456 567 678 789 890
4082```

Batch files are a bit arcane, it’s true, but the extensions added post Windows 2000 make it a lot more entertaining.