c++編程 輸入若幹個百分制成績，輸出對應的五分制成績，輸入結束後再分別輸出這五個分段的人數

NUM的值

#include<stdio.h>

#define NUM 10

void main()

{

int i;

int num[5]={0};

float a,c;

printf("Please input %d numbers\n",NUM);

for(i=0;i<NUM;i++)

{

scanf("%f",&a);

if(a>100||a<0)

{

printf("this is a error!\n");//如果不在範圍內請重新輸入另壹個數字

i--;

continue;

}

c=a*0.5;

printf("The percent conversion to fifty points is %6.1f\n",c);

if(0<=a&&a<20)

num[0]++;

if(20<=a&&a<40)

num[1]++;

if(40<=a&&a<60)

num[2]++;

if(60<=a&&a<80)

num[3]++;

if(80<=a&&a<100)

num[4]++;

}

for(i=0;i<5;i++)

printf("In between %d and %d is %5d numbers\n",20*i,20*(i+1),num[i]);

printf("\n");

}