PHP Math Exercises: Create a human-readable random string for a captcha

PHP math: Exercise-11 with Solution

Write a PHP function to create a human-readable random string for a captcha.

Sample Solution:

PHP Code:

// Define a function named random_string with a default length of 5
function random_string($length = 5)
    // Define a string of characters without vowels and 'x'
    $chars = 'bcdfghjklmnpqrstvwxyz';

    // Initialize an empty string to store the result
    $result = '';

    // Iterate through the specified length to generate random characters
    for ($x = 0; $x < $length; $x++)
        // Alternate between consonants and vowels while generating characters
        $result .= ($x % 2) ? $chars[mt_rand(13, 21)] : $chars[mt_rand(0, 12)];

    // Return the generated random string
    return $result;

// Call the random_string function and echo the result
echo random_string();




In the exercise above,

  • function random_string($length = 5): This line defines a function named "random_string()" with one parameter '$length', which has a default value of 5 if not provided.
  • $chars = 'bcdfghjklmnpqrstvwxyz';: This line defines a string of characters containing consonants excluding 'x'. Vowels and 'x' are omitted to avoid inappropriate strings.
  • $result = '';: This line initializes an empty string to store the generated random string.
  • for ($x = 0; $x < $length; $x++): This line starts a loop that iterates from 0 to the specified length, generating random characters.
  • $result .= ($x % 2) ? $chars[mt_rand(13, 21)] : $chars[mt_rand(0, 12)];: This line generates random characters alternately from consonants and vowels. It uses the modulus operator to determine whether the index of the character to be chosen is even or odd.
  • return $result;: This line returns the generated random string.
  • echo random_string();: This line calls the "random_string()" function without providing a length, so it uses the default length of 5, and echoes the generated random string.

Flowchart :

Flowchart: Create a human-readable random string for a captcha

PHP Code Editor:

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