作业3

1.0

#include <stdio.h>

int main(){    int a;    while(1)    {    printf("请输入一个实数:");    scanf("%d",&a);    if (a>=0)        printf("%d\n",a);    if (a<0)        printf("%d\n",-a);    }    return 0;}

2.0

#include <stdio.h>int main(){    int a;    while(1)    {    printf("请输入一个实数:");    scanf("%d",&a);    if (a%2==0)        printf("这个实数为偶数\n");    else        printf("这个数为奇数\n");    }    return 0;}

3.0

#include <stdio.h>#include<math.h>int main(){    int a,b,c,s,area;    while(1)    {    printf("请输入三角形的三条边a,b,c:");    scanf("%d%d%d",&a,&b,&c);    s=(a+b+c)/2;    area=sqrt(s*(s-a)*(s-b)*(s-c));    if (a+b>c&&a+c>b&&b+c>a)        printf("这个三角形的面积：area=%d\n",area);    else        printf("这个三角形不存在！\n");    }    return 0;}

4.0 

#include <stdio.h>#include<math.h>int main(){    int a,n,s1,s2,s3,s4,s5;    while(1)    {    printf("请输入存入的本金和时间a,n:");    scanf("%d%d",&a,&n);    s1=a*(1+0.0225)*1;    s2=a*(1+0.0243)*2;    s1=a*(1+0.0270)*3;    s1=a*(1+0.0288)*5;    s1=a*(1+0.0300)*8;    switch(n)    {    case 1:        printf("%d\n",s1);    break;    case 2:        printf("%d\n",s2);    break;    case 3:        printf("%d\n",s3);    break;    case 5:        printf("%d\n",s4);    break;    case 8:        printf("%d\n",s5);    break;    }    }    return 0;}