After i declare the variable as you suggested, it comes out another error, said 'use of uninitialized value $A in concatenation <.>.....'

#Main body

while (my $line = <TEMP>)
{   
    my $A;
    my $B;
    my @column = split (/,/,$line);
    if ($column[4] < $column[7])
       { $A = $direction[0];
       }else {$A = $direction[1]; }
    if ($column[5] < $column[8])
       { $B = $direction[2];
       }else {$B = $direction[3]; }
    my $dir = $A.$B;
    
     print OUTPUT $column[4],$comma,$column[5],$comma,$column[7],$comm
+a,$column[8],$comma,$dir,$comma,$nline;
 }

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In reply to Re^2: Use perl to do direction matching by hujunsimon
in thread Use perl to do direction matching by hujunsimon

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