PHP Basics

<?php
//Assignment one
//problem no one
// variable means container puts data temporay wise it's will be constant also when changed !
$fname = "Sujon";
$lname ="Shekh";

echo "My name first name is {$fname} and my last name is {$lname}\n";
printf ("My name first name is %s and my last name is %s\n",strtoupper($fname),strtoupper($lname));
printf ('My name first name is %2$s and my last name is %1$s',$fname,$lname); //$fname is Arguments!!
// printf can changed variable value and it's user friendly;
echo "\n";

//problem no two

$birthYears = 1993;
$recentYears = 2020;
$birthYears2 = $recentYears - $birthYears; // this operation called operand;
//number += 1 (+=Assingment operator); means number = number + 1 ;
echo "My Age is {$birthYears2} years old";

echo "\n";

//Problem no three

$d = 51;
$o =051;
$h = 0X5D;

printf ("Various Number System is %d and %d also %d\n",$d,$o,$h);
printf ("The Binary equivalent is %d to %b\n",$d,51);
printf ('The Binary equivalent is %1$d to %1$b',51); //place holder!
echo "\n";


//Problem no four
$product = 123.500;
$product2 = 63.213;
printf("Price is %07.2f,\n",$product);
printf("Price is %07.2f,\n",$product2);


//Problem no five
$food = "apple";
if ("Tuna" == $food || "salmon fish" == $food ||"shark" == $food ){ // "Tuna" == $food is scalar value;
    echo "{$food} is Vitamine 'D'";
}elseif("apple"== $food || "mango"== $food || "pineaple"==$food){
    echo "{$food} is Fruit";
}else{
    echo "its not avaiable in our store Sorry !!!!!!!";
}
echo "\n";

//problem no six

$year = 1900;

if ($year % 4 ==0 &&($year % 100 !=0 || $year % 400 ==0))//it's called Nested ! //if (true && true) can print if any where false it's turn over false;
    //if (false || true) can print if any where false it's turn over true;

   {
    echo "$year Leap Year";
}else{
    echo "$year not Leap Year";
}

echo "\n";

// problem no seven

$condition1 = false;
$condition2 = true;
$condition3 = false;
 if ($condition1 && $condition2 && $condition3){
    echo "Hello Sujon Shekh";
 }elseif ($condition1 && $condition2){
     echo "no 1";
 }elseif ($condition1){
     echo "no 2";
 }else {
    echo  "no 3";
 }
echo "\n";



// problem number Eight

$numb = 10 ;

$numberCheck = (12 == $numb) ? "Twelve" : ((10 == $numb) ? "Ten" : "A Number");  //Ternary Operator can handle many nested wise!
$numberCheck2 = ($numb %2 == 0) ? "Even Number " : "Odd Number";
echo $numberCheck;
echo "\n";
echo $numberCheck2;

echo PHP_EOL;

// Problem number nine

for ($i = 1; $i<=10; $i++){

    echo PHP_EOL;

   for( $j= 10-$i; $j >=1 ; $j--){
        echo "  ";
    }
    for ($j = 1; $j<= $i ; $j++ ){
        echo " * ";
    }
}
echo PHP_EOL;
//problem number ten

$n = 10;
for ($i = $n, $factorial = 1 ; $i > 1 ; $i--) {
    $factorial *= $i;
}
printf ("The factorial number of %d is %d",$n,$factorial);

//Problem number eleven

echo PHP_EOL;
echo "Fibonacchi series : ";

$very_old = 0;
$old = 1;
$new = 1;
for ($i=0; $i<10; $i++){

    echo $very_old. " ";

    $old = $new;
    $new = $very_old + $old;
    $very_old = $old;
}

// Problem number tweleve !!
echo PHP_EOL;
$x = 51;
$y = 51;
$sujon = $x <=> $y; // Spacesheep operator
if ($sujon == 1){
   echo "{$x} is greater than {$y}";
}elseif ($sujon ==0){
    echo "{$x} is equales to {$y}";
}elseif($sujon ==-1){
    echo "{$x} is smallar than {$y}";
}

//problem number thirteen

echo "\n";

$default_lat = 51.5;
$default_lon = 29.5;

$user_lat ;

$lat = $user_lat ?? $default_lat; //null coales operator better than ternary operator

echo $lat;

if (isset($user_lat)){
    $lat = $user_lat;
}else{
    $lat = $default_lat;
}