程序代码：

#include<stdlib.h>
#include<string.h>
#include<stdio.h>//递归实现n!
int n(int element)
{if(0==element)return 1;return element*n(element-1);
}//递归实现0-n的和
int sub_sum(int element)
{if(0==element)return 0;return element+sub_sum(element-1);
}//递归实现斐波那契 
int Fibonacci(int element)
{if(element<=1)return element;return Fibonacci(element-1)+Fibonacci(element-2);
}//递归实现二进制转换
void binary(int element)
{if(element==0)return;binary(element/2);printf("%d",element%2);
}//递归实现各个位数字之和
int Sum_bit(int element)
{if(element==0)return 0;return element%10+Sum_bit(element/10);
}//递归实现各个位数字乘积
int Pro_bit(int element)
{if(element==0)return 1;return element%10*Pro_bit(element/10);
}//递归实现单词逆置
void inversion(char *p,int low,int high)
{if(low<high){char t=*(p+low);*(p+low)=*(p+high);*(p+high)=t;inversion(p,low+1,high-1);}elsereturn;
}int main(int argc, const char *argv[])
{int element;printf("please input element:");scanf("%d",&element);//递归实现n！int num=n(element);printf("%d\n",num);//递归实现0-n和num=sub_sum(element);printf("%d\n",num);//递归实现斐波那契num=Fibonacci(element);printf("斐波那契数列第%d项为: %d\n",element,num);//递归实现二进制转换binary(element);puts("");//递归实现各个位数字之和int sum=Sum_bit(element);printf("%d\n",sum);//递归实现各个位数字乘积num=Pro_bit(element);printf("%d\n",num);char str[20]="";printf("please input string:");gets();gets(str);int len=strlen(str);//递归实现单词逆置inversion(str,0,len-1);puts(str);return 0;
}

运行结果：