# C Program to show Fibonacci Series

Write a C program , that prints all the Fibonacci numbers , which are smaller than or equal to a number k(k≥2) ,which was entered by the user.

• The Fibonacci numbers are a sequence of numbers,where then-th number of Fibonacci is defined as:
• Fib(0)=0,
• Fib(1)=1,
• Fib(n)=Fib(n-1)+Fib(n-2) Usage :> Input of k:21 > Fibonacci numbers<=21:01123581321

Solution 1 –

The solution below will answer following questions :
1. Write a program to generate the Fibonacci series in C.
2. Fibonacci series in C using for loop.
3. How to print Fibonacci series in C.
4. Write a program to print Fibonacci series inC.
5. How to find Fibonacci series in C programming.
6. Basic C programs Fibonacci series.

```/**
Fibonacci series in C using for loop by Codebind.com
*/
#include <stdio.h>
#include <stdlib.h>

int main () {
int r=0,a=0,n,b=1,i,c;
char redo;
do {
a=0;
b=1;
printf("enter the the value of n:");
scanf("%d", &n);
if(n>100) {
printf("enter some lessor value\n");
}
else {
for (i=0;i<=n;i++) {
c=a+b;
a=b;
b=c;
printf("serial no.%d => ", i+1);
printf("%d\n",a);
}
printf("enter y or Y to continue:");
scanf("%s", &redo);
printf("\n");
}
}
while(redo=='y'||redo=='Y');

return 0;
}

/*
OUTPUT
enter the the value of n:10
serial no.1 => 1
serial no.2 => 1
serial no.3 => 2
serial no.4 => 3
serial no.5 => 5
serial no.6 => 8
serial no.7 => 13
serial no.8 => 21
serial no.9 => 34
serial no.10 => 55
serial no.11 => 89
enter y or Y to continue:
*/
```

Solution 2 –

If we want to Write a program to generate the Fibonacci series in C using recursion, the follow the solution below :

```/**
Fibonacci series in C using recursion by codebind.com
*/

#include <stdio.h>
#include <stdlib.h>

int Fibonacci(int x) {
if (x < 2){
return x;
}
return (Fibonacci (x - 1) + Fibonacci (x - 2));
}

int main(void) {
int number;
printf( "Please enter a positive integer: ");
scanf("%d", &number);
if (number < 0)
printf( "That is not a positive integer.\n");
else
printf("%d Fibonacci is: %d\n", number, Fibonacci(number));
return 0;
}

/*
OUTPUT
Please enter a positive integer: 10
10 Fibonacci is: 55

*/
```

Solution 3 –

The solution below will answer following questions :
1. Fibonacci series using array in C
2. Fibonacci series program in C language
3. Source code of Fibonacci series inC
4.Write a program to print Fibonacci series in C

```/**
Fibonacci series in C using array by codebind.com
*/

#include <stdio.h>
#include <stdlib.h>

int main(void) {
int i,number;
long int arr[40];

printf( "Enter the number : \n");
scanf("%d", &number);

arr[0]=0;
arr[1]=1;

for(i = 2; i< number ; i++){
arr[i] = arr[i-1] + arr[i-2];
}

printf("Fibonacci series is: \n");
for(i=0; i< number; i++)
printf("%d\n", arr[i]);
return 0;
}

/*
OUTPUT
Enter the number :
10
Fibonacci series is:
0
1
1
2
3
5
8
13
21
34
*/
```