Exercise 3: Function Write a function named word_count that accepts a string as its parameter and returns the number of words in the string. A word is a sequence of one or more non-space characters (any character other than ' '). For example, the call of word_count("hello, how are you?") should return 4. Constraints: • Do not use any data structures such as arrays to help you solve this problem. • Do not use the String function explode on this problem. • But you can declare as many simple variables like Integer, String, etc. as you like. Keep it simple.

I am writing a PHP program.

<?php  

function word_count($string){   // function that takes a string a parameter and returns the number of words in that string

  $space = 0;   // this variable is used in order to detect space, new line and tab spaces in a string

  $words = 1; // this variable is used to identify word presence in string

  $include = $space;  //used to maintain the state of $words and $space

  $counter = 0; // this counts the number of words in the string

  $i = 0; //this moves through each character of the string

  while ($i < strlen($string)){ // iterates through every character of string until the last character of string is reached

      if ($string[$i] == " "||$string[$i] == "\n" || $string[$i] == "\t")  //if the space or new line or tab space is identified in the string

          $include = $space; //set the state of include as space if the next character is a space newline or a tab space

      else if ($include == $space) {  //if next character is a word and current state i.e. $include holds $space

          $include = $words;   //  then set the state i.e. $include as $words

          ++$counter; } //increments i to move to next character at each iteration

      ++$i;  } //returns the number of words in a string

  return $counter; }

$str = "Hello, how are you ";  //sample string

echo "Words: " . word_count($str);  // calls word_count function to return number of words in str.

?>  

Explanation:

The program has a function word_count that accepts a string as its parameter and returns the number of words in the string. In the function there are three variables $space and $words and $include used as state variables. For instance $space identifies space, new line and tab spaces in the $string so it specifies that a space has occurred. $words identifies words in the $string so it specifies that a word has occurred. $include holds this state information. $i moves through every character of the $string and when a space occurs in the $string then the state $include is set to $space. When a word occurs then state $include is set to $words. $counter variable, which is used to count the number of words is incremented to 1 when previous state is $space and next character is a word character. Every time a word is seen in the string, this variable is incremented to 1 to keep track of number of words in the string. When $i reaches the end of the string then this loop stops and counter returns the number of words in the $string.