unpack - strange behaviour

[ifiaz]

The following program run:

($field1, $field2, $field3, $field4, $field5) = unpack("A4 A1 A3 A1
A*", "this is v strange");

print "|$field1|\n";
print "|$field2|\n";
print "|$field3|\n";
print "|$field4|\n";
print "|$field5|\n";

and the result is this:

|this|
||
|is|
|v|
| strange|

But, I expect a space for $field2 i.e. | |

Why $field4 can print with a single character and
$field2 can't. Am I missing something?

 

[Anno Siegel]

The following program run:

($field1, $field2, $field3, $field4, $field5) = unpack("A4 A1 A3 A1
A*", "this is v strange");

print "|$field1|\n";
print "|$field2|\n";
print "|$field3|\n";
print "|$field4|\n";
print "|$field5|\n";

and the result is this:

|this|
||
|is|
|v|
| strange|

But, I expect a space for $field2 i.e. | |

Why $field4 can print with a single character and
$field2 can't. Am I missing something?

Yes. Perldoc -f pack:

as necessary. When unpacking, "A" strips
trailing spaces and nulls, "Z" strips

Use "a" instead.

Anno