Most online batch scripts come with a lot of quote issues.
if %var%==abc echo Test
This code works - when the content of %var%
does not contains space or other special characters. Now let's assume %var%
contains 1 whitespace. Now cmd.exe
sees:
if ==abc echo Test
This would cause a failure because cmd.exe
doesn't understand this syntax.
if "%var%"=="abc" echo Test
Using quotes, cmd.exe
sees the entire %var%
(including space and special characters) as only one normal string. Yet this is not the safest comparison method. The safest one uses echo
, pipe
, and findstr
.
cd C:\User\Spaced Name\Spaced FileName.txt
cd
would only change directory to C:\User\Spaced
, as cd
only accepts one path argument.
Simply by adding quotes around the path, the issue would be solved.
cd "C:\User\Spaced Name\Spaced FileName.txt"
There are also a few examples that work better using quotes, like the set /a
statement, etc. But, when one works on strings that contain spaces or special characters, it is usually much safe to use quotes.
Spaghetti code means a code snippet that uses many, and often confusing structures. Such as GOTO
s, exceptions and inconsistent code.
@echo off
set /a counter=0
:Loop
set /a counter=%counter% + 1
echo %counter%
if %counter% equ 10 goto :exit
goto :Loop
:exit
This program comes with plenty of jumps, making us harder to know what exactly the script is doing.
@echo off
for /l %%G in (0,1,10) echo %%G
Using less GOTO
s, we reduced the amount of code greatly, and we can focus on the actual code.
Consider the following statements.
:endGame
if %player1Score% gtr %player2Score% goto :player1wins
if %player1Score% lss %player2Score% goto :player2wins
goto :tie
:player1wins
echo player 1 wins
goto :eof
:player2wins
echo player 2 wins
goto :eof
:tie
echo tie
goto :eof
This snippet requires lots of goto
statements and can be confusing to debug. To simplify these statements, we can use call
command. Here is the above script at a better condition.
:endGame
if %player1Score% gtr %player2Score% call :message player 1 wins
if %player1Score% lss %player2Score% call :message player 2 wins
if %player1Score% equ %player2Score% call :message tie
goto :eof
:message
echo %*
goto :eof
Both scripts output the exact same result, but the new script is much shorter and clearer.