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List of latest and most asked PHP practical interviews questions & answers

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Core PHP Practical Interview Questions

In this blog post I am sharing a list of some most asked PHP interview questions & answers. These are very useful and helpful for the freshers and experienced developer too. I have taken these questions from different sources and listed here at one place.

Ques. How to reverse a string without using any builtin function?

Ans: 

 
<?php
  $str = 'My name is Diwakar Kumar';
  $len = 0;
  while(isset($str[$len]) != '')
      $len++;
  for($i = $len ; $i >= 0 ; $i--)
  {
      echo @$str[$i];
  }
Ques: Write a function to check if a given string is a palindrome or not.

Ans:

1st Method:

<?php	
function isPalindrome($str) {
    $str = strtolower(preg_replace('/[^a-zA-Z0-9]/', '', $str)); // Convert to lowercase and remove non-alphanumeric characters
    $reverse = strrev($str); // Reverse the string
    return $str === $reverse; // Compare original and reversed string
}
2nd Method:

<?php
function isPalindrome($str) {
    $left = 0;
    $right = strlen($str) - 1;
    while ($left < $right) {
        if($str[$left] != $str[$right]) {
            return false;
        }
        $left++;
        $right--;
    }
    return true;
}

Ques: Write a function to calculate the factorial of a given number.

Ans:


<?php
function factorial($num) {
    if ($num <= 1) {
        return 1;
    } else {
        return $num * factorial($num - 1);
    }
}

Ques: Write a function to reverse a string.

Ans:


<?php
function reverseString($str) {
    $reverse = '';
    $length = strlen($str);
    for ($i = $length - 1; $i >= 0; $i--) {
        $reverse .= $str[$i];
    }
    return $reverse;
}

Ques: Write a function to check if a given number is prime or not.

Ans:


<?php
function isPrime($num) {
    if ($num <= 1) {
        return false;
    }
    for ($i = 2; $i <= sqrt($num); $i++) {
        if ($num % $i == 0) {
            return false;
        }
    }
    return true;
}

Ques: Write a function to reverse the order of words in a given string.

Ans:


<?php
function reverseWords($str) {
    $words = [];
    $word = '';
    for ($i = 0; $i < strlen($str); $i++) {
        if ($str[$i] == ' ') {
            $words[] = $word;
            $word = '';
        } else {
            $word .= $str[$i];
        }
    }
    $words[] = $word;
    $reverse = '';
    for ($i = count($words) - 1; $i >= 0; $i--) {
        $reverse .= $words[$i] . ' ';
    }
    return trim($reverse);
}

Ques: Write a function to find the maximum element in an array.

Ans:


<?php
function findMax($arr) {
    $max = $arr[0];
    for ($i = 1; $i < count($arr); $i++) {
        if ($arr[$i] > $max) {
            $max = $arr[$i];
        }
    }
    return $max;
}

Ques: Write a function to generate the Fibonacci sequence up to a given number.

Ans:


<?php
function fibonacci($num) {
    $fib = [0, 1];
    for ($i = 2; $i <= $num; $i++) {
        $fib[$i] = $fib[$i - 1] + $fib[$i - 2];
    }
    return $fib;
}

Ques: Write a function to remove all duplicate elements in an array.

Ans:


<?php
function removeDuplicates($arr) {
    $result = [];
    foreach ($arr as $value) {
        if (!in_array($value, $result)) {
            $result[] = $value;
        }
    }
    return $result;
}

Some pattern Questions:

Ques: Write a PHP program to print the following pattern.

1
2 3
4 5 6
7 8 9 10

Ans:


<?php
$num = 1;
for ($i = 1; $i <= 4; $i++) {
    for ($j = 1; $j <= $i; $j++) {
        echo $num . ' ';
        $num++;
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

*
**
***
****
*****

Ans:


<?php
for ($i = 1; $i <= 5; $i++) {
    for ($j = 1; $j <= $i; $j++) {
        echo '*';
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

    *
   **
  ***
 ****
*****

Ans:


<?php
for ($i = 1; $i <= 5; $i++) {
    for ($j = 1; $j <= 5 - $i; $j++) {
        echo ' ';
    }
    for ($k = 1; $k <= $i; $k++) {
        echo '*';
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

    1
   232
  34543
 4567654
567898765

Ans:


<?php
for ($i = 1; $i <= 5; $i++) {
    for ($j = 1; $j <= 5 - $i; $j++) {
        echo ' ';
    }
    $num = $i;
    for ($k = 1; $k <= $i; $k++) {
        echo $num;
        $num++;
    }
    $num--;
    for ($l = 1; $l <= $i - 1; $l++) {
        $num--;
        echo $num;
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

A
BB
CCC
DDDD
EEEEE

Ans:


<?php
for ($i = 65; $i <= 69; $i++) {
    for ($j = 65; $j <= $i; $j++) {
        echo chr($i);
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

    A
   B C
  D E F
 G H I J
K L M N O

Ans:


<?php
$alpha = 65;
for ($i = 1; $i <= 5; $i++) {
    for ($j = 1; $j <= 5 - $i; $j++) {
        echo ' ';
    }
    for ($k = 1; $k <= $i; $k++) {
        echo chr($alpha) . ' ';
        $alpha++;
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

1
22
333
4444
55555

Ans:


<?php
for ($i = 1; $i <= 5; $i++) {
    for ($j = 1; $j <= $i; $j++) {
        echo $i;
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

A
BA
CBA
DCBA
EDCBA

Ans:


<?php
for ($i = 65; $i <= 69; $i++) {
    for ($j = $i; $j >= 65; $j--) {
        echo chr($j);
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

1
10
101
1010
10101

Ans:


<?php
for ($i = 1; $i <= 5; $i++) {
    for ($j = 1; $j <= $i; $j++) {
        if ($j % 2 == 1) {
            echo '1';
        } else {
            echo '0';
        }
    }
    echo "\n";
}

Ques: Write a PHP program to print the following pattern.

*****
 ****
  ***
   **
    *

Ans:


<?php
for ($i = 1; $i <= 5; $i++) {
    for ($j = 1; $j <= $i - 1; $j++) {
        echo ' ';
    }
    for ($k = 1; $k <= 6 - $i; $k++) {
        echo '*';
    }
    echo "\n";
}

Some problem solving questions:

Ques: Write a PHP program to find the largest and smallest elements in an array.

Ans:


<?php
$numbers = array(12, 6, 23, 8, 5, 19);
$smallest = $numbers[0];
$largest = $numbers[0];

foreach ($numbers as $num) {
    if ($num < $smallest) {
        $smallest = $num;
    }
    if ($num > $largest) {
        $largest = $num;
    }
}

echo "The smallest number in the array is: " . $smallest . "\n";
echo "The largest number in the array is: " . $largest . "\n";

Ques: Write a PHP program to find the sum of all even numbers and odds numbers in an array.

Ans:


<?php
$numbers = array(12, 6, 23, 8, 5, 19);
$even_sum = 0;
$odd_sum = 0;

foreach ($numbers as $num) {
    if ($num % 2 == 0) {
        $even_sum += $num;
    } else {
        $odd_sum += $num;
    }
}

echo "The sum of even numbers in the array is: " . $even_sum . "\n";
echo "The sum of odd numbers in the array is: " . $odd_sum . "\n";

Ques: Create a function that takes a string consisting of lowercase letters, uppercase letters and numbers and returns the string sorted in the same way as the examples below.

examples:
	sorting("eA2a1E") ➞ "aAeE12"
	sorting("Re4r") ➞ "erR4"
	sorting("6jnM31Q") ➞ "jMnQ136"
	sorting("846ZIbo") ➞ "bIoZ468"

Ans:


<?php
function sorting($str) {
    $lowercase = $uppercase = $numbers = '';
    for ($i = 0; $i < strlen($str); $i++) {
        $char = $str[$i];
        if (ctype_lower($char)) {
            $lowercase .= $char;
        } else if (ctype_upper($char)) {
            $uppercase .= $char;
        } else if (ctype_digit($char)) {
            $numbers .= $char;
        }
    }
    $sortedStr = $lowercase . $uppercase . $numbers;
    return $sortedStr;
}
Note: I will try my best to keep this post updated.
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