:time0  计算时间差 （封装）
@echo off&setlocal&set /a n=0&rem code 随风 @bbs.bathome.net
for /f "tokens=1-8 delims=.: " %%a in ("%~1:%~2") do (
set /a n+=10%%a%%100*360000+10%%b%%100*6000+10%%c%%100*100+10%%d%%100
set /a n-=10%%e%%100*360000+10%%f%%100*6000+10%%g%%100*100+10%%h%%100)
set /a s=n/360000,n=n%%360000,f=n/6000,n=n%%6000,m=n/100,n=n%%100
set "ok=%s% 小时 %f% 分钟 %m% 秒 %n% 毫秒"
endlocal&set %~3=%ok:-=%&goto :EOF
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@echo off&setlocal enabledelayedexpansion
set "str="
for /f "delims=" %%a in ('set . 2^>nul') do set "%%a="
for /l %%a in (1 1 10) do set .%%a=%%a&set str=!str! %%a
set t=%time%
for /l %%j in (1 1 100) do (
  for /f "delims=" %%a in ("%str%") do (
    for %%i in (%%a) do echo %%i >nul
))
call time0 %t% %time% ok
echo  for /f 命令 直接显示1000个结果 %ok%
echo.
for /l %%a in (1 1 10) do call :loop %%a
pause
:loop
set t=%time%
for /f "delims=" %%a in ('set .') do echo %%a >nul
call time0 %t% %time% ok
echo 运行%1次 %ok%
goto :EOF
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@echo off&setlocal enabledelayedexpansion
for /l %%a in (1 1 10) do set .%%a=%%a
set t=%time%
for /l %%a in (1 1 100) do set . >nul&echo a>nul
call time0 %t% %time% ok
echo  %ok%
pause
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@echo off
echo a>c.txt
set t=%time%
findstr .* c.txt>nul
call time0 %t% %time% ok
echo %Ok%
set t=%time%
findstr .* a.txt>nul
call time0 %t% %time% ok
echo %Ok%
set t=%time%
for /l %%a in (1 1 100) do findstr .* c.txt>nul
call time0 %t% %time% ok
echo %Ok%
set t=%time%
for /l %%a in (1 1 100) do findstr .* a.txt>nul
call time0 %t% %time% ok
echo %Ok%
pause
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@echo off&setlocal enabledelayedexpansion
cd.>c.txt
for /l %%a in (1 1 5000) do (
   echo bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb>>c.txt
)
call :jjj 1
call :loop 1 a&echo.
call :jjj 1
call :loop 2 a&echo.
call :jjj 98
call :loop 100 a&echo.
call :loop 5000 b&echo.
pause
:loop
set t=%time%
for /f "delims=" %%a in ('findstr "%2" c.txt') do set a=a
call time0 %t% %time% ok
echo 匹配结果为%1行 %ok%
goto :EOF
:jjj
for /l %%a in (1 1 %~1) do echo a>>c.txt
goto :EOF
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@echo off
set t=%time%
echo a|findstr .*>nul
call time0 %t% %time% ok
echo  %ok%
pause
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@echo off&setlocal enabledelayedexpansion
set t=%time%
cd.>d.txt
for /f "delims=" %%a in (c.txt) do >>d.txt echo %%a
call time0 %t% %time% ok
echo  %ok%
set t=%time%
echo.>nul 3>d.txt
for /f "delims=" %%a in (c.txt) do echo %%a
echo.>nul 4>con
call time0 %t% %time% ok
echo  %ok%
set t=%time%
findstr .* c.txt>e.txt
call time0 %t% %time% ok
echo  %ok%
pause
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::这样需要启用N次IO
::十万行代码的测试结果： 0 小时 3 分钟 25 秒 68 毫秒
for /f "delims=" %%a in (c.txt) do >>d.txt echo %%a
::这样只需要启用一次IO
::十万行代码的测试结果： 0 小时 0 分钟 2 秒 70 毫秒
(for /f "delims=" %%a in (c.txt) do (
  echo %%a
))>e.txt
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