实验四-在分支循环结构中调用自定义函数

#include<stdio.h>
int main(void)
{
int i,n;
double x,y;

printf("Enter n:");
scanf("%d",&n);

for(i=1,i<=1,i++){
printf("Enter x:");
scanf("%if",&x);
if(x<=0){
printf("Error!");

}

else if(x<=50){
y=0.53*x;
}

else(x>50){
y=0.58*x;

}
printf("y=f(%f)=%.1.0f\n,x,y);

}
return 0;

}

#include<stdio.h>
int main(void)
{
int x,y;
printf("Enter x:\n");
scanf_s("%d",&x);
if(x<0){

y = -1;
}
else if(x==0){

y=0;
}
else{
y=1;

}
printf("y=%d\n",y);
return 0;
}

/* 输入一个正整数 n，再输入 n 个学生的成绩，计算平均成绩，并统计所有及格学生的人数 */
#include<stdio.h>
int main(void)
{
int count,i,num;
double grade,total;
num=0;
total=0;
count=0;
printf("Enter grade:\n");
scanf_s("%Lf",&grade);
while(grade>=0){
total=total+grade;
num++;
if(grade>=60)
count++;
scanf_s("%Lf",&grade);
}
if(num!=0){
printf("Grade average is %.2f\n",total/num);
printf("The number of 及格的人 is %d\n",count);
}
else
printf("Grade average is 0\n");
return 0;
}

#include<stdio.h>
int main(void)
{
int i,year,n;
printf("请输入n");
scanf_s("%d",&n);
printf("Input -1 to quit:");
scanf_s("%d", &year);
if( year==-1 )
return -1;
for(i=1;i<=n;i++){
printf("请输入年份：");
scanf_s("%d",&year);
if((year%4==0&&year%100!=0)||(year%400==0)){
printf("这一年是闰年！\n");
}
else{
printf("这一年不是闰年！\n");
}
}

return 0;
}

#include <stdio.h>
int main(void)
{
char ch;
printf("输入成绩：");
ch=getchar();
switch(ch){
case 'A':
printf("90-100\n");
break;
case 'B':
printf("80-89\n");
break;
case 'C':
printf("70-79\n");
break;
case 'D':
printf("60-69\n");
break;
case 'E':
printf("0-59\n");
break;
default:
printf("Invalid input\n");
break;
}
return 0;
}