Hi walkingcow,

Adding my 2 cents here ...

A trick I like for comparisons against a constant (for both arrays and scalars), is to put the constant on the left side of the == operator.

This has the nice effect of making it illegal to accidentally drop one of the '=' signs.

For example, in: 


use strict;
use warnings;

my @array = ( 1, 2, 3 );
print "@array\n";

# Time passes...

if (@array = 10) {       # A typo -- should have been "(@array == 10)"
    print "@array\n";    # Causes an assignment, and a TRUE evaluation
+!
} else {
    print "The array doesn't have 10 values\n";
}

# Prints:
#   1 2 3
#   10


@array = ( 1, 2, 3 );
print "@array\n";

# Time passes...

if (10 == @array) {      # Can't accidentally do "(10 = @array)"
    print "@array\n";    # without getting a fatal error.
} else {
    print "The array doesn't have 10 values\n";
}


# Prints:
#   1 2 3
#   The array doesn't have 10 values

[download]

If you were to accidentally change "==" to "=" in "if (10 == @array" (or someone in the future did the same), the resulting error would reveal it: 

Can't modify constant item in scalar assignment at x.pl line 26,
near "@array) "
Execution of x.pl aborted due to compilation errors.

[download]

I use it all the time now by habit, and I never have to worry about accidentally assigning instead of comparing. Of course, ymmv...

s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/

In reply to Re: Test Number of Elements In Array by liverpole
in thread Test Number of Elements In Array by walkingthecow

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