PHP Program to Count the Occurrence of Each Characters

Given a String, the task is to count the occurrences of each character using PHP. This article explores various approaches to achieve this task using PHP, These are:

Approach 1: Using Arrays and str_split() Function

This approach involves splitting the input string into an array of individual characters using str_split() function. The array_count_values() function is then applied to obtain the count of each unique character in the array. Finally, a loop iterates through the counts and prints the occurrences for each character.

<?php 

function countChars($str) { 
	$chars = str_split($str); 
	$count = array_count_values($chars); 

	foreach ($count as $char => $occurrences) { 
		echo "'$char' occurs $occurrences times.\n"; 
	} 
} 

// Driver code 
$str = "Welcome GeeksforGeeks"; 

countChars($str); 

?>

'W' occurs 1 times.
'e' occurs 6 times.
'l' occurs 1 times.
'c' occurs 1 times.
'o' occurs 2 times.
'm' occurs 1 times.
' ' occurs 1 times.
'G' occurs 2 times.
'k' occurs 2 times.
's' occurs 2 times.
...

Approach 2: Using str_split() and array_count_values() Functions

This approach combines str_split() and array_count_values() function directly within the function. It streamlines the process by avoiding the intermediate variable for the characters array.

<?php 

function countChars($str) { 
	$count = array_count_values(str_split($str)); 

	foreach ($count as $char => $occurrences) { 
		echo "'$char' occurs $occurrences times.\n"; 
	} 
} 

// Driver code 
$str = "Welcome GeeksforGeeks"; 

countChars($str); 

?>

'W' occurs 1 times.
'e' occurs 6 times.
'l' occurs 1 times.
'c' occurs 1 times.
'o' occurs 2 times.
'm' occurs 1 times.
' ' occurs 1 times.
'G' occurs 2 times.
'k' occurs 2 times.
's' occurs 2 times.
...

Approach 3: Using preg_match_all() Function

This approach leverages regular expressions through preg_match_all() to match all characters in the Unicode string (/./u). The resulting matches are then processed using array_count_values() to get the count of each character, and a loop prints the occurrences.

<?php 

function countChars($str) { 
	preg_match_all('/./u', $str, $matches); 
	$count = array_count_values($matches[0]); 

	foreach ($count as $char => $occurrences) { 
		echo "'$char' occurs $occurrences times.\n"; 
	} 
} 

// Driver code 
$str = "Welcome GeeksforGeeks"; 

countChars($str); 

?>

'W' occurs 1 times.
'e' occurs 6 times.
'l' occurs 1 times.
'c' occurs 1 times.
'o' occurs 2 times.
'm' occurs 1 times.
' ' occurs 1 times.
'G' occurs 2 times.
'k' occurs 2 times.
's' occurs 2 times.
...

Approach 4: Using count_chars() Function

Another efficient way to count the occurrences of each character in a string is by using the count_chars() function. This function returns an array with the frequency of every byte-value (character) used in the string.

Example: This approach is particularly useful when you need a quick and efficient way to count the occurrences of each character in a string using PHP.

<?php
function countCharacterOccurrences($inputString) {
    // Use count_chars() to get the frequency of each character
    $charCounts = count_chars($inputString, 1);
    
    // Iterate through the resulting array and print the occurrences of each character
    foreach ($charCounts as $char => $count) {
        echo chr($char) . " => " . $count . "\n";
    }
}

// Sample usage
$inputString = "GeeksforGeeks";
countCharacterOccurrences($inputString);

?>

G => 2
e => 4
f => 1
k => 2
o => 1
r => 1
s => 2