Capitalize last letter of a string

How can I capitalize only the last letter of a string.

For example:

hello

becomes:

hellO

Convoluted but fun:

echo strrev(ucfirst(strrev("hello")));

Demo: http://ideone.com/7QK5B

as a function:

function uclast($str) {
    return strrev(ucfirst(strrev($str)));
}

When $s is your string (Demo):

$s[-1] = strtoupper($s[-1]);

Or in form of a function:

function uclast(string $s): string
{
  $s[-1] = strtoupper($s[-1]);
  return $s;
}

And for your extended needs to have everything lower-case except the last character explicitly upper-case:

function uclast(string $s): string
{
  if ("" === $s) {
    return $s;
  }

  $s = strtolower($s);
  $s[-1] = strtoupper($s[-1]);

  return $s;
}

There are two parts to this. First, you need to know how to get parts of strings. For that, you need the substr() function.

Next, there is a function for capitalizing a string called strtotupper().

$thestring="Testing testing 3 2 1. aaaa";
echo substr($thestring, 0, strlen($thestring)-2) . strtoupper(substr($thestring, -1));

Here's an algorithm:

  1. Split the string s = xyz where x is the part of
     the string before the last letter, y is the last
     letter, and z is the part of the string that comes
     after the last letter.
  2. Compute y = Y, where Y is the upper-case equivalent
     of y.
  3. Emit S = xYz

Lowercase / uppercase / mixed character case for everything following can be used

<?php
    $word = "HELLO";

    //or

    $word = "hello";

    //or

    $word = "HeLLo";

    $word = strrev(ucfirst(strrev(strtolower($word))));

    echo $word;
?>

Output for all words

hellO

$string = 'ana-nd';

echo str_replace(substr($string, -3), strtoupper('_'.substr($string, -2)), $string);

// Output: ana_ND


$string = 'anand';

echo str_replace(substr($string, -2), strtoupper(substr($string, -2)), $string);

// Output: anaND