作业六

#include<stdio.h>
int sign (int x)
{
    if(x<0)
     return -1;
    if(x>0)
     return 1;
    else
     return 0;
} 
int main()
{
    int x;
    scanf("%d",&x);
    printf("%d\n",sign(x));
    return 0;
}

#include<stdio.h>
int even(int n)
{
    if(n%2==0)
     return 1;
    else
     return 0;
}
int main()
{
    int n,x,y;
    printf("请输入正整数：\n");
    do{
        scanf("%d",&n);
        y=even(n);
        if(y==0){
            x=x+n;
        }
    }while(n>0);
    printf("x=%d\n",x);
    return 0;
}

#include<stdio.h>
int prime (int m)
{
    int i;
    for(i=2;i<=m/2;i++)
        if(m%i==0)
         return 0;
        else
         return 1;
}
int main()
{
    int m,n,cnt,sum;
    cnt=0;
    sum=0;
    printf("请输入两个正整数：");
    scanf("%d%d",&m,&n);
    for(m=0;m<=n;m++) 
    {
        if(prime(m))
        {
            cnt++;
            sum+=m;
        } 
    }
    printf("cnt=%d,sum=%d\n",cnt,sum)
    return 0; 
}

#include<stdio.h>
int countdigit(int number,int digit)
{
    int i=0;
    while(number>0)
    {
        if(number%10==digit)
        i++;
        number=number/10;
    }
    return i;
}
int main()
{
    int number,digit,sum;
    printf("请输入一个数字：\n");
    scanf("%d",&number);
    printf("请输入要计算的数字：\n");
    scanf("%d",&digit);
    sum=countdigit(number,digit);
    printf("共有%d个",sum);
    return 0; 
}

#include<stdio.h>
int is(int number)
{
    int n=0,m=0,i=0;
    scanf("%d%d",&n,&m);
    for(i=n;i<=m;i++)
    {
        if(is(i));{
        printf("%d\n",i);
        }
    }
    {
        int x,y,z;
        x=number/100;
        y=number/10-i*10;
        z=number%10;
        if(number==x*x*x+y*y*y+z*z*z){
            return 1;
        }
        else
        {
            return 0;
        }
        return number;
    } 
}