What 's wrong with this fibonacci function?

Question

#include <stdio.h>
int fib(int a){
    if(a==0)
        return 0;
    else if(a==1)
        return 1;
    else
        return fib(a) = fib(a-1) + fib(a-2);
}

int main(){
    int n=0;
    printf("type: ");
    scanf("%d", &n);
    printf("%d", fib(n));

    return 0;
}

Answer 1

try this:

return fib(a-1) + fib(a-2);

instead of:

return fib(a) = fib(a-1) + fib(a-2);

Answer 2

#include <stdio.h>
int fib(int a){
    int nextterm,t1=0,t2=1;
 for(int i = 1;i<=a;++i)
 {
    printf("\nfibonacci series :  ");
    printf("%d",t1);
    nextterm=t1+t2;
    t1=t2;
    t2=nextterm;
 }
}

void main(){
    int n;
    printf("type: ");
    scanf("%d", &n);
    printf("%d", fib(n));

}