Brackets & Parentheses and Batch Execution Purgatory

[lmstearn]

This is in relation to this post regarding the System() command in C, but I thought a separate thread is more apt.

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@echo on & SET RR="Value" & IF DEFINED RR (echo Value Detected & pause >nul) else (echo Nada Value & pause >nul) & pause >nul

The line runs fine except it breaks before the statement after the else block. However, reversing the condition:

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@echo on & SET RR="Value" & IF NOT DEFINED RR (echo Value Detected & pause >nul) else (echo Nada Value & pause >nul) & pause >nul

The code assembles fine, but now the last statement is executed. It's becoming increasingly apparent that even with the assistance of \n, getting "one-line" code to work with parentheses in System() is becoming rather a challenge.
Has anyone any insights to share here? Thanks.

[jeb]

Hi lmstearn,

the problem here is the & operator after the ELSE block.

You could read your code like

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echo on 
SET RR="Value"
IF DEFINED RR (
    echo Value Detected
    pause >nul
) else (
    echo Nada Value
    pause >nul) & pause >nul

The point is that the last & pause > nul is part of the ELSE block, so it's part of the complete IF-block, to change this, you could enclose the IF into parenthesis

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echo on & SET RR="Value" & (IF DEFINED RR (echo Value Detected & pause >nul) else (echo Nada Value & pause >nul)) & pause >nul

[lmstearn]

Ah, thanks Jeb. Yep, that saves worrying about attempting to replace the & with CRLF and the like, which no doubt you would have a solution for.