Can someone explain to me this 'counting sentences' php code? - php

Question

I have a task to count sentences without using str_word_count, my senior gave it to me but I am not able to understand. Can someone explain it?
I need to understand the variable and how it works.
<?php
$sentences = "this book are bigger than encyclopedia";
function countSentences($sentences) {
$y = "";
$numberOfSentences = 0;
$index = 0;
while($sentences != $y) {
$y .= $sentences[$index];
if ($sentences[$index] == " ") {
$numberOfSentences++;
}
$index++;
}
$numberOfSentences++;
return $numberOfSentences;
}
echo countSentences($sentences);
?>
The output is
6

Answer 1

It's something very trivial, I'd say.
The task is to count words in a sentence. A sentence is an string (a sequence of characters) that are letters or white spaces (space, new line, etc.)...
Now, what's a word of the sentence? It is a distinct group of letters that "don't touch" other group of letters; meaning words (group of letters) are separated from each other with white space (let's say just a normal blank space)
So the simplest algorithm to count words consist in:
- $words_count_variable = 0
- go through all the characters, one-by-one
- each time you find a space, it means a new word just ended before that, and you have to increase your $words_count_variable
- lastly, you'll find the end of the string, and that means a word just ended before that, so you'll increase for the last time your $words_count_variable
Take "this is a sentence".
We set $words_count_variable = 0;
Your while cycle will analyze:
"t"
"h"
"i"
"s"
" " -> blank space: a word just ended -> $words_count_variable++ (becomes 1)
"i"
"s"
" " -> blank space: a word just ended -> $words_count_variable++ (becomes 2)
"a"
" " -> blank space: a word just ended -> $words_count_variable++ (becomes 3)
"s"
"e"
"n"
...
"n"
"c"
"e"
-> end reached: a word just ended -> $words_count_variable++ (becomes 4)
So, 4.
4 words counted.
Hope this was helpful.

Answer 2

Basicaly, it is just counting the number of space in a sentence.
<?php
$sentences = "this book are bigger than encyclopedia";
function countSentences($sentences) {
$y = ""; // Temporary variable used to reach all chars in $sentences during the loop
$numberOfSentences = 0; // Counter of words
$index = 0; // Array index used for $sentences
// Reach all chars from $sentences (char by char)
while($sentences != $y) {
$y .= $sentences[$index]; // Adding the current char in $y
// If current char is a space, we increase the counter of word
if ($sentences[$index] == " "){
$numberOfSentences++;
}
$index++; // Increment the index used with $sentences in order to reach the next char in the next loop round
}
$numberOfSentences++; // Additional incrementation to count the last word
return $numberOfSentences;
}
echo countSentences($sentences);
?>
Be aware that this function will have wrong results on several case, for example if you have two spaces following, this function will count 2 words instead of one.