C program to find nth term of Fibonacci series unlimited number | Unlimited Fibonacci series in C Language | upto nth number Fibonacci series in C language

C program to find nth term of Fibonacci series unlimited number | Unlimited Fibonacci series  in C Language | upto nth number Fibonacci series in C language

#define MAX 2100  
#include 
#include 
#include 
void print(char x[]); 
void add(char x[], char y[], char z[]); 

int main() 
{  
    int i=0,j,num; 
    char n_minus1[MAX]="1",n_minus2[MAX]="1",nth[MAX]=""; 
    printf("This is a program to print fibonacci sequence upto desired term.(max 10000)\n"); 
    printf("\nenter a natural number upto which do you want fibonacci series\n");
    scanf("%d",&num); 
    if(    num<1||num>10000) 
    { 
        printf("The desired term index was either invalid or greater than 10000\n"); 
        exit(0); 
    }
    printf("\noptions:\n1. print only %dth term\n2. print all terms\n",num);
    scanf("%d",&j);
    switch(j)
    {
        case 1: 
                if(num<2){
                printf("The first term is 1\n");
                break;
                }
                if(num<3){
                printf("The second term is 1\n");
                break;
                }
                for(i=2;i<num;i++)
                {
                  add(nth,n_minus1,n_minus2);
                  strcpy(n_minus2,n_minus1);
                  strcpy(n_minus1,nth);
                }
                printf("The %dth term is ",num);
                print(nth);
                break;
        case 2:    printf("\nFibonacci series upto %dth term\n\n",num);
                printf("term \tvalue\n",num);
                printf("%4d \t1\n",1);
                if(num<2)
                break;
                printf("%4d \t1\n",2);
                if(num<3)
                break;
                for(i=2;i<num;i++)
                {
                  add(nth,n_minus1,n_minus2);
                  printf("%4d\t",i+1);
                  print(nth);
                  strcpy(n_minus2,n_minus1);
                  strcpy(n_minus1,nth);
                }
                break;
        default: printf("Invalid choice...!!! \tExiting\n");
                exit(0);
    }
    printf("\n\nprgram finished successfully.\t press any key to continue\n");
    getchar(); 
    return 0; 
} 

void print(char x[]) 
{ 
    int i; 
    for(i=strlen(x)-1;i>=0;i--) 
    { 
        putchar(x[i]); 
        if(i%5==0) 
        putchar(' '); 
    } 
    putchar('\n'); 
    return; 
} 

void add(char x[],char y[],char z[]) 
{ 
    int i,ylen,zlen,equal;
    char c = 0,temp;
    ylen = strlen(y);
    zlen = strlen(z);
    equal = (ylen == zlen) ? 1 : 0; 
    for(i=0;i<zlen;i++) 
    { 
        x[i]=c + y[i] + z[i] - '0'; 
        if( x[i]-'0' > 9)
        {
            x[i]-=10;
            c=1;
        }
        else
        c=0; 
    }
    if(equal)
    {
        if(c!=0)
        {
            x[i]=c + '0';
            x[i+1]='\0';
        }
    }
    else
    {
        x[i]=c + y[i];
        x[i+1]='\0';
    } 
    return; 
}