美国大西洋:编程统计n名学生某门功课考试的分数段人数.(用C语言!!!)

#include<iostream.h>
void main()
{
int iIn;
int duan100(0),duan90(0),duan80(0),duan70(0),duan60(0);
cout<<"输入成绩(输入负数时退出):\n";
cin>>iIn;
while(iIn>=0)
{
switch(iIn/10)
{
case 10:
case 9:
duan100++;
break;
case 8:
duan90++;
break;
case 7:
duan80++;
break;
case 6:
duan70++;
break;
default:
duan60++;
}
cout<<"成绩:";
cin>>iIn;
}
cout<<"60分以下:"<<duan60<<"\n60~70:"<<duan70<<"\n70~80:"<<duan80<<"\n80~90:"<<duan90<<"\n大于90:"<<duan100<<endl;
}

int chengji[n];
int duan60,duan70,duan80,duan90,duan100;
for (int i = 0; i < n; i++)
{
if (chengji[i] < 60)
duan60++;
else if (chengji[i] >=60 && chengji[i] <70)
duan70++;
else if (chengji[i] >=70 && chengji[i] <80)
duan80++;
else if (chengji[i] >=80 && chengji[i] <90)
duan90++;
else duan100++;
}

cout<<"<60:"<<duan60<<" 60~70:"<<duan70<<" 70~80:"<<duan80
<<"80~90:"<<duan90<<">90:"<<duan100;

#include<iostream.h>
void main()
{
float chengji[n];
int duan60=duan70=duan80=duan90=duan100=0;
for (int i = 0; i < n; i++)
{
if (chengji[i] < 60)
duan60++;
else if (chengji[i] >=60 && chengji[i] <70)
duan70++;
else if (chengji[i] >=70 && chengji[i] <80)
duan80++;
else if (chengji[i] >=80 && chengji[i] <90)
duan90++;
else if (chengji[i] >=90 && chengji[i]<=100)
duan100++;
}

cout<<"<60:"<<duan60<<" 60~70:"<<duan70<<" 70~80:"<<duan80
<<"80~90:"<<duan90<<">90:"<<duan100;
}