Hello jobsworth,

Perhaps this will shed some light:

(1) Without warnings:

23:59 >perl -E "$c = 1; say(length $c);"
1

23:59 >perl -E "say(length $c);"


23:59 >perl -E "$c = sprintf('%d', $c); say(length $c);"
1

23:59 >
[download]

(2) With warnings:

23:59 >perl -wE "$c = 1; say(length $c);"
1

 0:01 >perl -wE "say(length $c);"
Name "main::c" used only once: possible typo at -e line 1.
Use of uninitialized value in say at -e line 1.


 0:01 >perl -wE "$c = sprintf('%d', $c); say(length $c);"
Use of uninitialized value $c in sprintf at -e line 1.
1

 0:01 >
[download]

Hope that helps,