当$ STRING以“\\ t \\ t”结尾时，如何使split（/ \\ t /，$ STRING）检测空值？

Question

How can I make split(/\\t/, $STRING) detect empty items when $STRING ends with "\\t\\t" ?

Using Perl script, I am trying to split strings based on as a separator between items then count and use these items. But, when the strings end with a combination s, the script doesn't count empty items.

Example:

string="value1\\tvalue2\\t\\t\\t\\t" (value1, value2 and 4 empty items)

but it counts 2 items (value1, value2):

$STRING="value1\tvalue2\t\t\t\t";
print $STRING."\n";
my @F = split(/\t/, $STRING);
print scalar(@F)."\n";

# The number of items must match the number of header name
if( scalar(@F) == 6 )
            {
                    print  "Done \n";
            }

the code prints:

value1  value2      
2

while what is expected is:

value1  value2  
6

Answer 1

Change the split line by adding -1 as a parameter:

my @F = split(/\t/, $STRING, -1);

Output:

value1  value2              
6
Done 

Per perldoc split , the parameters to split are PATTERN, EXPR, LIMIT . In your current situation, "LIMIT is omitted so "trailing empty fields are stripped."

By adding the -1 value for LIMIT :

If LIMIT is negative, it is treated as if it were instead arbitrarily large; as many fields as possible are produced.

So a negative final argument prevents split from discarding trailing fields.