循环通过文件保存到变量 [英] loop through file saving to variable

问题描述

我现在有以下的bat文件工作（允许一个文件添加到文件的每一行的末尾） - 请参见：
bat文件：将if，for和变量一起使用

  @echo off 
 setLocal EnableDelayedExpansion 
 
 IF EXIST％FileToModify1％（
 for / ftokens = * delims =%% a in（％FileToModify1％）do（
 echo %% a注意：某些条件适用>>％SaveFile1％
）
 ）
  

但是，我想保存每一行到一个变量（包括新的行符号）），然后将变量回传到文件末尾。因为文件中有几行文件，每行保存到一个文件的效率真的很低。

我试过谷歌搜索，但答案不符合我的情况。基本上我需要语法连接和保存到一个变量（累积类似+ =在C＃），并且还使用新行...

解决方案

实际上，你不需要把一切都放在一个变量，你只需要将重定向放在另一个位置。
试试这个：

  @echo off 
 setlocal EnableDelayedExpansion 
 
 ％FileToModify1％（
 for / Fusebackq delims =%% a in（％FileToModify1％）do（
 echo %% a注：某些条件适用
）
）> ％SaveFile1％
 
 endlocal 
  

请注意，文件被忽略/ F ，因此它们不会传输到新文件。此外，对于/ F 忽略以; 开头的行（除非更改 eol 选项 - 请参阅 for /？）。

我修改了 for / F 选项：

• no delims ，因此每行都是按原样输出的（tokens = * delims =，如果存在，每个行都会删除前导空格）;


• usebackq 允许在中包含文件规范， ;

---

附录A

如果您仍然想将文件内容存储到变量中，可以这样做：

  @echo off 
 setlocal EnableDelayedExpansion 
 
 rem强制执行以下命令后的两个空行：
 set LF = ^ 
 
 
如果存在％FileToModify1％ （
 setFileContent =
 for / Fusebackq delims =%% a in（％FileToModify1％）do（
 setFileContent =！FileContent！%% a Note ：某些条件适用！LF！
）
（echo！FileContent！）> ％SaveFile1％
）
 
 endlocal 
  

内容存储在变量 FileContent 中，包括附录注意：某些条件适用。 LF 持有新行符号。

注意： $ b变量的长度是非常有限的（据我所知，从Windows XP和2047字节早8191字节）！

[参考文献： br>
将文件输出存储到变量（上一个代码段）;

说明dos-batch newline变量hack的工作原理]

---

附录B

或者，您可以将文件内容存储在数组中，如下所示：

  @echo off 
 setlocal EnableDelayedExpansion 
 
如果存在％FileToModify1％（
 set / A cnt = 0 
 for / Fusebackq delims =%% a in（％FileToModify1％）do（
 set / A cnt + = 1 
 setLine [！cnt！] = %% a注意：某些条件适用于
）
 
（对于/ L %% i in（1,1，！cnt！）do（
 echo！Line [ ％％一世]！ 
））> ％SaveFile1％
）
 
 endlocal 
  

的文件存储在数组 Line [1] ， Line [2] ，行[3] 等，包括附录注意：某些条件适用。 cnt 包含总数，这是数组大小。

注意：

实际上，这不是一个真正的数组数据类型，因为它在批处理中不存在，它是一个具有数组风格命名的标量变量的集合（ Line [1] ， Line [2] ，...）;因此可以将其称为伪数组。

[参考文献：

将文件输出存储到变量（第一个代码段）;

如何在批处理文件中从txt文件创建数组？]

I now have the following bat file working (which allows one to add text to the end of each line of a file) -- please see also: bat file: Use of if, for and a variable all together

@echo off
setLocal EnableDelayedExpansion

IF EXIST "%FileToModify1%"  (
  for /f "tokens=* delims= " %%a in (%FileToModify1%) do (
    echo %%a   Note:  certain conditions apply  >> "%SaveFile1%"
  ) 
)

However, I would like to save each line to a variable (including the new line symbol(s)) and then echo the variable to a file at the end. Since there are several lines in the file it is really inefficient to save to a file with each line.

I tried googling this, but the answers do not fit my situation...

essentially I need the syntax for concatenating and saving to a variable (cumulatively like "+=" in C#), and also using the new lines...

解决方案

Actually you do not need to put everything into a variable, you just need to place the redirection at another position. Try this:

@echo off
setlocal EnableDelayedExpansion

if exist "%FileToModify1%" (
    for /F "usebackq delims=" %%a in ("%FileToModify1%") do (
        echo %%a   Note:  certain conditions apply
    )
) > "%SaveFile1%"

endlocal

Note that empty lines in the original file are ignored by for /F, so they are not transferred to the new file. Also lines starting with ; are ignored by for /F (unless you change the eol option -- see for /?).

I modified the for /F options:

• no delims are allowed, so the each line is output as is (with "tokens=* delims= ", leading spaces are removed from each line if present);
• usebackq allows to surround the file specification in "" which is helpful if it contains spaces;

---

Appendix A

If you still want to store the file content into a variable, you can do this:

@echo off
setlocal EnableDelayedExpansion

rem the two empty lines after the following command are mandatory:
set LF=^


if exist "%FileToModify1%" (
    set "FileContent="
    for /F "usebackq delims=" %%a in ("%FileToModify1%") do (
        set "FileContent=!FileContent!%%a   Note:  certain conditions apply!LF!"
    )
    (echo !FileContent!) > "%SaveFile1%"
)

endlocal

The file content is stored in variable FileContent, including the appendix Note: certain conditions apply. LF holds the new-line symbol.

Note:
The length of a variable is very limited (as far as I know, 8191 bytes since Windows XP and 2047 bytes earlier)!

[References:
Store file output into variable (last code fragment);
Explain how dos-batch newline variable hack works]

---

Appendix B

Alternatively, you could store the file content in a array, like this:

@echo off
setlocal EnableDelayedExpansion

if exist "%FileToModify1%" (
    set /A cnt=0
    for /F "usebackq delims=" %%a in ("%FileToModify1%") do (
        set /A cnt+=1
        set "Line[!cnt!]=%%a   Note:  certain conditions apply"
    )

    (for /L %%i in (1,1,!cnt!) do (
        echo !Line[%%i]!
    )) > "%SaveFile1%"
)

endlocal

Each line of the file is stored in an array Line[1], Line[2], Line[3], etc., including the appendix Note: certain conditions apply. cnt contains the total number of lines, which is the array size.

Note:
Actually this is not a true array data type as such does not exist in batch, it is a collection of scalar variables with an array-style naming (Line[1], Line[2],...); therefore one might call it pseudo-array.

[References:
Store file output into variable (first code fragment);
How to create an array from txt file within a batch file?]

这篇关于循环通过文件保存到变量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！