Enable and Disable Delayed Expansion, what does it do?

Question

I\'ve seen SETLOCAL ENABLEDELAYEDEXPANSION & SETLOCAL DISABLEDELAYEDEXPANSION in many batch files but what do the commands actually do?

Answer 1

enabledelayeexpansion instructs cmd to recognise the syntax !var! which accesses the current value of var. disabledelayedexpansion turns this facility off, so !var! becomes simply that as a literal string.

Within a block statement (a parenthesised series of statements), the entire block is parsed and then executed. Any %var% within the block will be replaced by that variable's value at the time the block is parsed - before the block is executed - the same thing applies to a FOR ... DO (block).

Using !var! in place of %var% accesses the changed value of var.