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Fibonacci or not in C

## Write a program which checks a given integer is Fibonacci number or not.

#include<stdio.h>

void main()

{

int f,s,t,n,i,flg; //’f’ is 1st num,’s’ is 2nd num,’t’ for 3rd new generated num, ‘n’ is user defined, ‘i’ is for iterations, “flg” is Flag variable.

printf(“Enter a number : “);

if(n<0)

{

return;

}

f=flg=t=0; //set f,flg and t variables set as zero for check conditions.

if(n==0)

flg=1; //set flg variable as ‘1’ for founding the integer in series.

else

{

s=1; //set ‘s’ variable as ‘1’ to generate next numbers of series.

while(t<n)

{

t=f+s; //Generating next number in the series by adding preceding two integers.

if(n==t)

flg=1;

f=s;

s=t; //Shifting the last two terms of series to ‘f’ & ‘s’ for generating next number in the series.

}

}

if(flg==1)

printf(“Given integer is a Fibonacci number.\n”);

else

printf(“Given integer is Not Fibonacci number.\n”);

return;

}

Output:

i) Enter a number : 610

Given integer is a Fibonacci number.

ii) Enter a number : 812

Given integer is Not Fibonacci number.

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Task: Write a C program to print nth term in Fibonacci series.