1  print "Enter a temperature in Celsius:\n";
  2  $celsius = <STDIN>; # read a line of input
  3  chomp( $celsius );  # remove newline
  4  
  5  if ( $celsius =~ m/^[0-9]+$/ ) {
  6    $fahrenheit = ( $celsius * 9/5 ) + 32;
  7    print "$celsius C = $fahrenheit F\n";
  8  } else {
  9    print "Expecting a number, not \"$celsius\"\n";
 10  }