问题描述
20 年来，我一直在用数十种语言进行编程，但无论我多么努力，我都无法理解FOR"在 windows cmd shell 批处理文件中的工作原理.我读了
I've been programming in dozens of languages for 20 years but I could never understand how "FOR" work in windows cmd shell batch file, no matter how hard I tried. I read
http://www.ss64.com/nt/for.html
和互联网上的其他几篇文章，但仍然混淆并且无法完成任何事情.
and several other articles on the internet but still confuse and cannot accomplish anything.
谁能给我一个关于FOR"一般如何工作的简明解释?
Can anybody give me a concise explaination on how "FOR" works in general ?
对于更具体的问题，如何遍历 %PATH% 变量中的每个路径?我试过
For a little more specific question, how can I iterate through each path in %PATH% variable ?I've tried with
rem showpathenv.bat
for /f "delims=;" %%g in ("%PATH%") do echo %%g
那只会显示第一条路径，而不是全部.为什么 ?我做错了什么?
That'd show only the first path, not all of them. Why ? What I do wrong ?
推荐答案
没有一个答案实际有效.我已经设法自己找到了解决方案.这有点hackish，但它为我解决了问题:
None of the answers actually work. I've managed to find the solution myself.This is a bit hackish, but it solve the problem for me:
echo off
setlocal enableextensions
setlocal enabledelayedexpansion
set MAX_TRIES=100
set P=%PATH%
for /L %%a in (1, 1, %MAX_TRIES%) do (
for /F "delims=;" %%g in ("!P!") do (
echo %%g
set P=!P:%%g;=!
if "!P!" == "%%g" goto :eof
)
)
哦！我讨厌批处理文件编程！！
Oh ! I hate batch file programming !!
更新
Mark 的解决方案更简单，但它不适用于包含空格的路径.这是马克的解决方案的一个小修改版
Mark's solution is simpler but it won't work with path containing whitespace. This is a little-modified version of Mark's solution
echo off
setlocal enabledelayedexpansion
set NonBlankPath=%PATH: =#%
set TabbedPath=%NonBlankPath:;= %
for %%g in (%TabbedPath%) do (
set GG=%%g
echo !GG:#= !
)
这篇关于“for"是怎么来的?在 cmd 批处理文件中工作?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！