DOS批处理:SET变量并在(...)块内回显它 [英] DOS batch: SET variable and ECHO it within (...) block

问题描述

我对 set 不能在批处理文件中工作有问题；解决这个问题花了一段时间；起初我以为这与子程序调用有关……

I had a problem with set not working in a batch file; it took a while to distil the problem; at first I thought it was to do with subroutine calls...

脚本

@echo off
setlocal
set a=aaa
echo a = "%a%"
(
set b=bbb
echo b = "%b%"
)

产生输出

a = "aaa"
b = ""

我期望

a = "aaa"
b = "bbb"

请问为什么?是DOS中的错误吗?也许我不知道关于(...)命令分组语法的某些事情.

Why is this please? Is it a bug in DOS? Perhaps there's something about the (...) command grouping syntax that I'm unaware of.

谢谢.

推荐答案

用户延迟了扩展，！代替％

User delayed expansion and ! instead of %

@echo off
setlocal enableextensions enabledelayedexpansion
set a=aaa
echo a = "%a%"
(
set b=bbb
echo b = "!b!"
)

这篇关于DOS批处理:SET变量并在(...)块内回显它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！