for循环中的变量操作 [英] variable manipulation in a for loop

问题描述

所以我的批处理代码应该一个接一个地打印一串数字。我的问题似乎是卡在第一个字母。我有（我相信）一个操作命令来删除字符串的第一个数字，但它似乎并没有工作。例如，如果info.txt是12345678，那么：loop将会陷入1中。

 ：floop 
 for / F %% G IN（'TYPE info.txt'）DO call：line1 %% G 
 goto：end 
 
：line1 
 set / a cnt + = 1 
 set / a div =％cnt％％2 
 if％div％== 0 call：line2％1 
 goto：EOF 
 
：line2 
设置ord =％1 
 echo％ord％
暂停
 
：循环
暂停$ b $ set var =％ord％
 set char = ％var：〜0,1％
 set var =％var：〜1％
 echo％char％
 if NOT％var％== _ end goto loop 
 goto floop 
 
：end 
  

解决方案

：loop
pause
set var =％ord％$ b $ set char =％var：〜0,1％$ b $ set var =％var：〜 1％
echo％char％
if NOT％var％== _ end goto loop
goto floop


你的第一个问题是在这部分^^

你正在设置 var 到 ord 的值; char 到 var 的第一个字符。 var 到第一个之后的其余部分;显示 char （第一个字符），然后从 ord 中循环回到设置 var code $ c

$ b $ $ $ $ $ $ $ $ $
：loop
pause
set char =％var：〜0,1％$ b $ set var =％var：〜1％
echo％char％
如果不是％var％== _ end goto loop
goto floop


这样可以解决这个问题。

但是您应该考虑如果 var 不 终止 _end 。最终， var 将变为空，而 cmd 会尝试解释行

  if NOT == _ end goto loop 
  

它会调用一个语法错误。

（你可以通过编码来解决这个问题）

 ：OLD_loop 
 pause 
 set var =％ord％_end 
：loop 
  

$ b $ p
$ b

然而，当 var 被修剪为 _end ？ GOTO floop 将再次读取文件，从第一行开始，处理它，最终找到 var = _end ，返回到 floop ，呃 - 我们之前已经在这里了....一段时间后，cmd将用完因为处理你的文件会调用子程序，但是永远不会返回...

So my batch code is supposed to print out a string of numbers one by one. My problem is it seems to get stuck in the first letter. I have (I believe) an manipulation command to remove the first number of the string but it doesn't seem to work. If for example the info.txt would be 12345678 the :loop would get stuck in 1.

:floop
for /F %%G IN ('TYPE info.txt') DO call :line1 %%G
goto :end

:line1
set /a cnt+=1
set /a div=%cnt% %% 2
if %div% == 0 call :line2 %1
goto :EOF

:line2
set ord=%1
echo %ord%
pause

:loop
pause
set var=%ord%
set char=%var:~0,1%
set var=%var:~1%
echo %char%
if NOT %var%==_end goto loop
goto floop

:end

解决方案

:loop
pause
set var=%ord%
set char=%var:~0,1%
set var=%var:~1%
echo %char%
if NOT %var%==_end goto loop
goto floop

Your first problem is in this part^^

You are setting var to the value of ord; char to the first charater of var; var to the rest after the first; displaying char (the first character) and then looping back to setting var from ord...

:OLD_loop
pause
set var=%ord%
:loop
pause
set char=%var:~0,1%
set var=%var:~1%
echo %char%
if NOT %var%==_end goto loop
goto floop

This should cure that problem.

but you should then consider what happens if var does not terminate _end. Eventually, var will become empty, and cmd will try to interpret the line

if NOT ==_end goto loop

which it will call a syntax error.

(you could fix this by coding

:OLD_loop
pause
set var=%ord%_end
:loop

)

But then - what happens when var is trimmed down to _end? GOTO floop will read the file again, starting at the first line, processing it, eventually finding var=_end, back to floop, er - we've been here before.... After a while, cmd will run out of stack space because processing your file calls the subroutine, but never returns...

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