#include<iostream>
using namespace std;
int Fibonacci(int n);
int main()
{
    int num;
    while(cin>>num)
    {
        if(num>40||num<2)
            break;
        else
            cout<<"The Fibonacci Number for "<<num<<" is "<<Fibonacci(num)<<endl;
    }
    return 0;
}
int Fibonacci(int n)
{
    if(n==0)
        return 0;
    else
        if(n==1)return 1;
        else
            return Fibonacci(n-1)+Fibonacci(n-2);
}

1.your program never compute Fibonacci(0) and Fibonacci(1).
2.the output format of your program does not meet requirement.
3.you use recursive algorithm which might be over time-limits.

会超时

# include <stdio.h>
int main()
{
    int i,s[41];
    s[0]=0;
    s[1]=0;
    s[2]=1;
    s[3]=1;
    for(i=4;i<=41;++i)
        s[i]=s[i-1]+s[i-2];
    int a,b;
    while(scanf("%d",&a)!=EOF)
        printf ("The Fibonacci number for %d is %d\n",a,(s[a]+s[a-1]));    
    return 0;
}