# Fibonacci Series Program in PHP

In this post, you will learn different ways to write the Fibonacci series programs using the PHP programming language.

The Fibonacci series is the sequence of numbers in which the next number is the sum of the two previous numbers. The Fibonacci series was well-known hundreds of years earlier. The "Fibonacci" name came from the nickname "Bonacci".

We can easily remember the Fibonacci Sequence using the Fibonacci Day, which is November 23rd. The 23rd of November has the digits "1, 1, 2, 3", which is part of the sequence. In the above image, the first two numbers are 0 and 1. So, according to the Fibonacci rule, the third number is 1 (sum of 0 and 1). The fourth number is 2, and so on.

``````0 + 1 = 1 // 0, 1, 1
1 + 1 = 2 // 0, 1, 1, 2
1 + 2 = 3 // 0, 1, 1, 2, 3
2 + 3 = 5 // 0, 1, 1, 2, 3, 5``````

0 ,1 , 1, 2, 3, 5, 8, 13, 21, 34....

## Fibonacci Series Program in PHP using For Loop

Here, you will learn how to print the Fibonacci series using a for loop in PHP. In the below code, \$f1 contains the first number, i.e., 0, and \$f2 contains the second number, i.e., 1 and \$n contains the total fibonacci series number count.

``````<?php
\$f1 = 0;
\$f2 = 1;
\$n = 30;
echo \$f1;
echo '<br/>';
echo \$f2;
for(\$i = 1; \$i <= \$n; \$i++) {
\$f3 = \$f1 + \$f2;
\$f1 = \$f2;
\$f2 = \$f3;
echo \$f3 ."<br />";
}
?>``````

0
1
1
2
3
5
8
13
21
34
55
89
144
233
377
610
987
1597
2584
4181
6765
10946
17711
28657
46368
75025
121393
196418
317811
514229
832040
1346269

## Fibonacci Series Program in PHP using while loop

In the given PHP program, we have used the while loop to print the Fibonacci series up to 15 in PHP. First, we print the first and second numbers. Then we use the while loop where we get the next number by adding the previous two numbers and simultaneously swap the first number with the second and the second with the third.

``````<?php
\$n = 0;
\$a = 0;
\$b = 2;
echo "Fibonacci series upto 15 : ";
echo "\$a, \$b";

while (\$n < 16 )
{
\$c = \$b + \$a;
echo ", ";
echo "\$c";
\$a = \$b;
\$b = \$c;
\$n = \$n + 1;
}
?> ``````
Output of the above code:
``Fibonacci series upto 15 : 0, 2, 2, 4, 6, 10, 16, 26, 42, 68, 110, 178, 288, 466, 754, 1220, 1974, 3194 ``

## Fibonacci Series Program in PHP using Recursive Function

A recursion function is a function that is called by itself. In the given example, we call the recursion function to get the Fibonacci series. A recursion function continues until some condition is met to prevent it. That's why we use the if-else statement to break the infinite recursion.

``````<?php
echo "<h2>Fibonacci series upto 20 - </h2>";
echo "\n\n";
\$n = 15;

/* Recursive function  */
function recursive(\$n){
if(\$n == 0){
return 0;
}
else if( \$n == 1)
{
return 1;
}
else {
return (recursive(\$n-1) + recursive(\$n-2));
}
}
/* Call Function */
for (\$i = 0; \$i < \$n; \$i++){
echo recursive(\$i);
echo "\n";
}
?>``````

### Output of the above code

``````Fibonacci series upto 20 -

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377``````

## Fibonacci Series Program in PHP using the iterative way

In the given example, we print the first and second numbers. And then we send the flow to the iterative while loop where we get the next number by adding the previous two numbers and, simultaneously, we swap the first number with the second and the second with the third. So that we print the Fibonacci series.

``````<?php

function Fibonacci(\$n){

\$num1 = 0;
\$num2 = 1;

\$counter = 0;
while (\$counter < \$n){
echo ' '.\$num1;
\$num3 = \$num2 + \$num1;
\$num1 = \$num2;
\$num2 = \$num3;
\$counter = \$counter + 1;
}
}

// Driver Code
\$n = 12;
Fibonacci(\$n);
?>``````
Output of the above code:
``0 1 1 2 3 5 8 13 21 34 55 89``

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