用PHP计算单词中的字母数

Question

I want to create an array which has two columns. The output should contain only the existing letters in the word with their amounts.

The wanted output of the following code

a 3
s 2
p 1

What is wrong in the following PHP code?

<?php

$alpha = array('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','z','y');

$word = "saapas";

for ( $i = 0; $i < count($word); $i++ ) {
        echo $word[$i] . "
";

        $table[$word[$i]][]++;           // Problem here
}


// array_unique, array_combine and some method which can sort arrays by alphabets can be useful 

Answer 1

PHP has extensive array functions that do much of the heavy lifting for this:

$keys = range('a', 'z');
$values = array_fill(0, 26, 0);
$freq = array_combine($keys, $values);
$word = "saapas";
$len = strlen($word);
for ($i=0; $i<$len; $i++) {
  $letter = strtolower($word[$i]);
  if (array_key_exists($letter, $freq)) {
    $freq[$letter]++;
  }
}
print_r($freq);

Output:

Array
(
    [a] => 3
    [b] => 0
    [c] => 0
    [d] => 0
    [e] => 0
    [f] => 0
    [g] => 0
    [h] => 0
    [i] => 0
    [j] => 0
    [k] => 0
    [l] => 0
    [m] => 0
    [n] => 0
    [o] => 0
    [p] => 1
    [q] => 0
    [r] => 0
    [s] => 2
    [t] => 0
    [u] => 0
    [v] => 0
    [w] => 0
    [x] => 0
    [y] => 0
    [z] => 0
)

If you want to distinguish between uppercase and lowercase try:

$keys = array_merge(range('a', 'z'), range('A', 'Z'));
$values = array_fill(0, 52, 0);
$freq = array_combine($keys, $values);
$word = "saApas";
$len = strlen($word);
for ($i=0; $i<$len; $i++) {
  $letter = $word[$i];
  if (array_key_exists($letter, $freq)) {
    $freq[$letter]++;
  }
}
print_r($freq);

Or to count any characters:

$freq = array();
$word = "saApas";
$len = strlen($word);
for ($i=0; $i<$len; $i++) {
  $letter = $word[$i];
  if (array_key_exists($letter, $freq)) {
    $freq[$letter]++;
  } else {
    $freq[$letter] = 1;
  }
}
print_r($freq);