Batch File Set Variable not working [duplicate]

问题:

This question already has an answer here:

• Declaring and using a variable in Windows batch file (.BAT) 3 answers

I'm doing some simple setting of a variable in a BAT file. It's not setting the variable. There aren't any odd constructs, it's simple variable substitution using the same variable name. I reduced the BAT file to a simple proof of concept version:

set TESTVAR = "No Value"
ECHO var = %TESTVAR%
set TESTVAR = ""
ECHO var = %TESTVAR%
set TESTVAR = "New value"
ECHO var = %TESTVAR%

And the output shows that none of the SET commands seem to be working. What the heck am I missing here. I've been writing BAT files for years and I've never seen this before. Here's the output from running this test:

C:\Users\rs02130\Desktop>test

C:\Users\rs02130\Desktop>set TESTVAR = "No Value"

C:\Users\rs02130\Desktop>ECHO var =
var =

C:\Users\rs02130\Desktop>set TESTVAR = ""

C:\Users\rs02130\Desktop>ECHO var =
var =

C:\Users\rs02130\Desktop>set TESTVAR = "New value"

C:\Users\rs02130\Desktop>ECHO var =
var =
C:\Users\rs02130\Desktop>

I expect the first and third ECHO commands to display the values "No Value" and "New value". What the heck is going on?

回答1:

The problem is the spaces around the equal sign. This should do what you want.

set TESTVAR="No Value"
ECHO var = %TESTVAR%
set TESTVAR=""
ECHO var = %TESTVAR%
set TESTVAR="New value"
ECHO var = %TESTVAR%