C的一些简单习题（1）求2/1，3/2，5/3，…………前20项的和

#include <stdio.h>
void main()
{
float sum;
int div,dived,tmp;
dived=2;
div=1;
int i;
sum=0;
i=1;
while(i<=20)
{
 sum=sum+(float)dived/(float)div;
 tmp=div;
 div=dived;
 dived=dived+tmp;
 i++;
}
printf("the sum is %f",sum);
}