#!/usr/bin/env perl
use 5.010; use strict; use warnings;

my @s = ('John', 'John ', 'John Doe', 'John P. Doe'); # last 2 should match
for (@s){
  my @v = split /\s+\b/;  # split on whitespace followed by a word boundary
  if(@v > 1 ){           # if the split did any splitting
    say;                 # do stuff with the line or elements
  }
}