Saved Bookmarks
| 1. |
Solve : Win/Batch: Question in DOS IF command? |
|
Answer» Hi, different value of %task% displayed if you set and read a variable inside parentheses (brackets) you need to use "delayed expansion". Otherwise it will either keep the value it had before the parentheses or if it had none, be null. 1. put this line before the parenthetical structure (e.g. at the start of the batch file setlocal enabledelayedexpansion 2. A variable which may be set or changed inside parentheses needs to use exclamation marks ! and not percent symbols % @echo off setlocal enabledelayedexpansion set task=0 abd ^/? > nul REM %ERRORLEVEL% was set outside the parentheses REM so it keeps its value REM %task% was set to 0 and retains that value REM unless you use delayed expansion and REM exclamation marks IF %ERRORLEVEL% NEQ 0 ( CLS SET task=%ERRORLEVEL% echo errorlevel is %errorlevel% echo task_flag is !task! ) echo error !!! pause exitGot it. Thanks. Where can I found the information about "delayed expansion" and "A variable which may be set or changed inside parentheses needs to use exclamation marks ! and not percent symbols %"Google ?Billrich attacking me again, for his own painfully obvious reasons. When we FEEL that Googling is more useful than writing YADEE (yet another delayed expansion explanation) (I have done about 6) we say so. Here is a good link however. http://www.robvanderwoude.com/variableexpansion.php |
|