Ending a program with a period statement - c

Question

I am trying to code a Fibonacci generator, and so far I was able to calculate it and got accurate results, but I keep receiving trailing commas and I wanted to add a period(.) at the end of the result.
#include <stdio.h>
int f1=0,f2=1,i,sum=0,n,a;
printf("Please enter the number for Fibonacci numbers.\n");
scanf("%d",&n);
if(n==0){
printf("%d.",n);
}
else if(n==1){
a = n-1;
printf("%d, %d.",a,n);
}
else{
for(i=0;i<=n;i++){
printf("%d, ",f1);
sum = f1+f2;
f1 = f2;
f2 = sum;
}
}
return 0;
}
For example, n = 6
I wanted:
0, 1, 1, 2, 3, 5, 8.
What I got earlier:
0, 1, 1, 2, 3, 5, 8,

Answer 1

Fetching the idea from the comments:
// I'd prefer unsigned as negative numbers are meaningless anyway
unsigned int f1 = 0, f2 = 1;
unsigned int n = 7;
printf("0"); // 0 is printed in *any* case
while(--n) // or with for loop from 0 as long as < (not <= any more!)
// note the first value *is* printed already
{
printf(", %d", f2); // prepending the comma, one value is already there
// f2: now using the larger of the two,
// as the smaller *is* printed already
unsigned int sum = f1 + f2; // (limiting scope of to where it
// actually is needed)
f1 = f2;
f2 = sum;
}
puts(".");
Bonus: No special cases necessary any more...

Answer 2

Just start the loop with the second number :-)
else{ else{
printf("0"); // 0 here
for(i=0;i<=n;i++){ for(i=1;i<=n;i++){ // start at 1
printf("%d, ",f1); printf(", %d",f1); // change order
sum = f1+f2; sum = f1+f2;
f1 = f2; f1 = f2;
f2 = sum; f2 = sum;
} }
printf(".\n"); // add period
} }

Answer 3

If it was me, i'd keep the code simple, i wouldn't use negative indices, and i wouldn't start from position 1 instead of 0. What I would do is as follows:
#include <stdio.h>
int main(){
// Always initialise variables, integers cost nothing to initialise
// We use long because Fibonacci numbers can get quite large quite quickly.
long long int f1=0,f2=1,iterations=0;
printf("Please enter the number for Fibonacci numbers.\n");
if(scanf("%lld",&iterations)!=1){
// This means we've failed to read a number.
puts("Something is wrong with the input, exiting.");
return -1;
}
// ++iterations; // uncomment if you want iterations+1 Fibonacci numbers
for(long long int i=0;i<iterations;++i){
printf("%lld",f1);
int f3=f1+f2;
f1=f2;
f2=f3;
if(i<iterations-1){
printf(", ");
}
}
if(iterations>0){
puts(".");
}
return 0;
}
To compile and run:
martyn#Atlas:~$ gcc Deleteme.c
martyn#Atlas:~$ ./a.out
Please enter the number of Fibonacci numbers.
6
0, 1, 1, 2, 3, 5.
martyn#Atlas:~$
Note that your original program outputs 7 Fibonacci numbers, rather than 6. If you want 1 more than you input, then increment iterations before the loop, by doing something like ++iterations;

Answer 4

#include <stdio.h>
#include <stdlib.h>
int
main(int argc, char **argv)
{
int n = argc > 1 ? strtol(argv[1], NULL, 0) : 10;
int f[2] = {1,1};
while( n-- ) {
printf("%d%s", f[0], n ? ", " : ".\n");
int t = f[0] + f[1];
f[0] = f[1];
f[1] = t;
}
return 0;
}