DB<6> $rx->{"ping_$i"} = "abc"

  DB<7> p delete $rx->{"ping_$i"} || 0
abc                                          # not numeric
  DB<8> p "" || 0
0                                            # was false
  DB<9> p undef || 0
0                                            # was false
  DB<10> p " " || 0
                                             # " " is true
  DB<11> p "abc" || 0
abc                                          
  DB<12> p int "abc"
0                                            # not numeric evaluates to 0 tho in numeric context
  DB<13> p int "7abc"
7                                            # beware that leading ciphers are accepted tho 
  DB<14> use warnings; say int "7abc"
Argument "7abc" isn't numeric in int at ...  # but will thro a warning too
...
  DB<15> p int ""                            # the || 0 part is redundant in all false cases
0
  DB<16> p int " "                           # sic
0
  DB<17> p int undef                         # sic
0
  DB<18>