Multiple condition IF statement using grep and eq

[Anonymous Monk]

I have a IF statement in this form:

if (grep $_ == $F[1],73,89,121,101,117,69,77,67,115,81,97,65,113) {

That compares values held within $F1 to those listed. I wish to add an additional condition that checks another variable other than $F1 but i'm struggling somewhat with the syntax and how this will work with the grep. For example:

if (grep $_ == $F[1],73,89,121,101,117,69,77,67,115,81,97,65,113 && $inext eq "Global.SAM")

Each condition works individually, but the latter condition testing $inext is ignored when written in this form. Why is this happening and what could be a solution to the problem?

[toolic]

Use parentheses to group your terms.

Tip #6 from the Basic debugging checklist: B::Deparse

perl -MO=Deparse,p 

if (grep(($_ == $F[1]), 73, 89, 121, 101, 117, 69, 77, 67, 115, 81, 97
+, 65, $inext eq 'Global.SAM')) {

Change your code to:

if ( (grep $_ == $F[1],73,89,121,101,117,69,77,67,115,81,97,65,113) &&
+ ($inext eq "Global.SAM") ) {

[Anonymous Monk]

Thank you! I knew it would be something simple. That tip is going to be super useful too.

[Marshall]

As further suggestion, move the "cheap test" to the front. Grep implies a foreach loop and is much more "expensive" than a simple equality test. The "if" statement is executed from left to right - don't bother with the grep if the first test fails.

Also consider the block form of grep:

if ($inext eq "Global.SAM" and
    grep{$_ == $F[1]} 73,89,121,101,117,69,77,67,115,81,97,65,113)
{}

"and" is a lower priority operator than "&&" so no extra parens required.