Logical Expressions with emply tag

[lei]

Dear Forum Experts,

While working with logical expressions to search files, I encountered an intriguing issue.

Here's the expression I employed:

Code Select Expand

-if ($IFD0:XPAuthor=~/catherine/i) or ($IFD0:Model=~/eva/i)

The problem arises when XPAuthor is not initialized; the entire expression fails regardless of whether the second condition is true or false. I had expected the "or" operator to allow evaluation of the second expression if the first one is false (either due to the tag not being initialized or not equal to "catherine"). However, this was not the case.

To ensure the condition functions correctly, I had to check if the tag exists before assessing its value, resulting in the following adjustment:

Code Select Expand

-if ($IFD0:XPAuthor and $IFD0:XPAuthor=~/catherine/i) or ($IFD0:Model=~/eva/i)

This workaround feels cumbersome. Is there a more efficient way to achieve the desired outcome without the need for preliminary testing?

Thank you in advance for your assistance!

[Phil Harvey]

You can either use the -f option to set undefined tags to "-", or the -m option to set undefined tags to "".  Both of these options have other side effects, so you should read up on them to see which is best for you.

- Phil

[lei]

You can either use the -f option to set undefined tags to "-", or the -m option to set undefined tags to "".  Both of these options have other side effects, so you should read up on them to see which is best for you.

- Phil

Great! That's much easier. Thanks!