How does perl recognise end of variable while printing? -

how perl recognise end of variable?

for example, code:

use warnings; $a = 10; print "value of $a:::"; 

output:

use of uninitialized value $a:: in concatenation (.) or string @ tryprint.pl line 6. value of : 

why consider $a:: , not $a: or $a:::

this works:

print "value of $a\:::"; 

prints:

value of 10::: 

:: used print/access variable package/symbol table. eg, access scalar variable x in package abc, perl uses $abc::x abc name of symbol table , x variable. similarly, when used $a:::, perl thought there package name 'a' , variable name :, , hence error.

see example below:

our $a = 10; {         $a=20;         print "lexical $a \n";         print "value of $main::a"; }