PHP - Groups of Data: Working with Arrays(array_key_exists)

Learning PHP

開発環境

• OS X El Capitan - Apple (OS)
• Emacs (Text Editor)
• PHP 7.0 (プログラミング言語)

Learning PHP: A Gentle Introduction to the Web's Most Popular Language (David Sklar (著)、 O'Reilly Media)のChapter 4.(Groups of Data: Working with Arrays)のExercises 3.(No. 2075)を取り組んでみる。

Exercises 3.(No. 2075)

コード(Emacs)

$locations_and_populations
  = [['New York', 'NY',8175133],
     ['Los Angeles', 'CA' , 3792621],
     ['Chicago', 'IL' , 2695598],
     ['HOuston', 'TX' , 2100263],
     ['Philadelphia', 'PA' , 1526006],
     ['Phoenix', 'AZ' , 1445632],
     ['San Antonio', 'TX' , 1327407],
     ['San Diego', 'CA' , 1307402],
     ['Dallas', 'TX' , 1197816],
     ['San Jose', 'CA' , 945942]];

$total = 0;
$state_population_totals = array();
foreach ($locations_and_populations as $loc_and_pop) {
  $city = $loc_and_pop[0];
  $state = $loc_and_pop[1];
  $population = $loc_and_pop[2];
  if (array_key_exists($state, $state_population_totals)) {
    $state_population_totals[$state] += $population;
  } else {
    $state_population_totals[$state] = $population;
  }
  $total += $population;
  print "$city, $state: $population\n";
}
print "total: $total\n\n";

foreach ($state_population_totals as $state => $population) {
  print "$state: $population\n";
}

入出力結果(Terminal, Interactive shell)

$ php70 -a < sample3.php
Interactive shell

New York, NY: 8175133
Los Angeles, CA: 3792621
Chicago, IL: 2695598
HOuston, TX: 2100263
Philadelphia, PA: 1526006
Phoenix, AZ: 1445632
San Antonio, TX: 1327407
San Diego, CA: 1307402
Dallas, TX: 1197816
San Jose, CA: 945942
total: 24513820

NY: 8175133
CA: 6045965
IL: 2695598
TX: 4625486
PA: 1526006
AZ: 1445632
$