Syntax error when asking if a variable equals another variable in batch

问题

Here is my code:

if %magic%==%weakness% set /a damage=%random%*3/32767+12
if %magic==%resistance% set /a damage=%random%*3/32767+5
echo Your attack does %damage% damage.

I keep getting a syntax error when I run this. What am I doing wrong?

回答1:

You should always use quotes around your variables or use delayed expansion, to avoid problems when one or both variables are empty.

Btw. in the second line you missed one percent

if "%magic%"=="%weakness%" set /a damage=%random%*3/32767+12
if "%magic%"=="%resistance%" set /a damage=%random%*3/32767+5
echo Your attack does %damage% damage.

Or with delayed expansion

setlocal EnableDelayedExpansion
if !magic!==!weakness! set /a damage=%random%*3/32767+12
if !magic!==!resistance! set /a damage=%random%*3/32767+5
echo Your attack does !damage! damage.

来源：https://stackoverflow.com/questions/18536743/syntax-error-when-asking-if-a-variable-equals-another-variable-in-batch