CODEWITHSUNDEEP
batch-file
ps-aux
ps-aux

Reputation: 12174

Batch file input not working correctly when in if block

When using set /p inside this if block. The variable input is not set to the input value. It is set only on second invocation of the script (as if it was set only after echo %input% line).

 if "%1"=="" (
        echo "You have to specify the name of the file."
        set /p input=File name: 
        echo %input%
        pause

 ) else (
        ...
 )

What can I do to have variable input set to values which was actually entered?

Upvotes: 0

Views: 81

Answers (2)

Julien
Julien

Reputation: 2246

You need to use delayed expansion.

In the Batch language, inside a FOR or a IF, the variables are "expanded" before and not during command execution. ( expanded = the variable is remplaced by its value )

For example, the following IF test

IF condition (
foo
bar
)

is interpreted as if condition foo & bar

So if a variable is set in foo and this same variable is used in bar, it's the previous value of the variable ( the one before entering the loop ) that is used in bar.

It's kinda disturbing but that how Batch works... So ithe set is working correctly, it's just a special way of working.

You must write SETLOCAL ENABLEDELAYEDEXPANSION at the beginning of your code and the variable whose expansion should be delayed must be surrounded by ! instead of %.

So echo %input% become echo !input!

Upvotes: 2

Endoro
Endoro

Reputation: 37589

you don't need delayed expansion here. Example:

 if "%1"=="" (
        echo "You have to specify the name of the file."
        set /p input=File name: 
        call echo %%input%%
        pause

 ) else (
        ...
 )

Upvotes: 3

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