China DOS Union

The system is 2k
set /p con="Continue (Y/N):"

set con=%con:y=Y%
set con=%con:n=N%

if %con%==Y goto continue
if %con%==N goto out
Written in a cmd script, while the program is running, echo %con%
I found that con at this point is y=Y
That is to say, con is now equal to the expression y=Y
Then when if does the check it becomes if y=Y==Y goto continue
But this line gives a syntax error in 2003, and I don't know why
Also, after executing set con=%con:y=Y% at the command line
echo %con% at this point con is equal to Y
Why does the command behave differently at the command line and in a script?

IF /I  ==  ……

The if /i parameter can judge without distinguishing uppercase or lowercase～：）

Then this line set con=%con:y=Y%
when written in a cmd script
why does con become y=Y? I don't understand

Also in 2003
if /i %con%==Y goto continue
it still gives an error

To prevent conflicts caused by empty variables or unexpected symbols, you must

IF /I  ==

You must wrap the variable being compared with some kind of symbol, like the " " square brackets above, so that if can read it clearly and cleanly. With well-structured code, the chance of errors is smaller～：）

The if /i parameter already ignores case, so there is no need to write the line set con=%con:y=Y% anymore～：）


If you don't like using the equals sign for comparison, then if also provides the following forms:

    EQU - equal to

    NEQ - not equal to

    LSS - less than

    LEQ - less than or equal to

    GTR - greater than

    GEQ - greater than or equal to

[ Last edited by redtek on 2006-12-19 at 10:25 AM ]

Got it, thanks redtek

Not bad, learned something.