delay有效无效的输出效果

delay(無効)

rem delay(無効).bat

@echo off
set a=1
set /a a+=1& echo %a%
pause>nul

输出结果：1

delay(有效)

delay(有効).bat

@echo off
setlocal enabledelayedexpansion
set a=1
rem set /a a+=1& echo %a%
set /a a+=1& echo !a!
pause>nul

输出结果：2