[数值计算] 批处理for命令里面的set /a为何显示的值不对？

@echo off
setlocal enabledelayedexpansion
set b=0
for /l %%a in (1,1,10) do (
    set /a b+=1
    echo !b!
)
echo !b!
pause
复制代码

@echo off&setlocal enabledelayedexpansion
echo office2003 所有文件下载 >office.htm
echo ^<br /^> >>office.htm
echo ^<table width="1200" height="400" border="2" cellpadding="0" cellspacing="0" class="tb"^> >>office.htm
set /a s=0
echo ^<tr^> >>office.htm
for %%a in (office\*.*) do (
    set /a s+=1
    echo ^<td^>^<a href="%%a"target="_blank" style="text-decoration:none"^>%%~nxa^</a^>^</td^> >>office.htm
    if %s:~-1%==5 echo ^</tr^>^<tr^> >>office.htm
    if %s:~-1%==0 echo ^</tr^>^<tr^> >>office.htm
    )
pause
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@echo off
setlocal enabledelayedexpansion
set b=0
for /l %%a in (1,1,10) do (
set /a b=!b!+1
echo !b!
)
echo %b%
pause
复制代码

@echo off&setlocal enabledelayedexpansion
set b=0
for /l %%a in (1,1,10) do (
set /a b=!b!+1
echo !b!
)
echo %b%
pause
复制代码

setlocal enabledelayedexpansion
复制代码