作业5

#include<stdio.h>
int main()
{
    int i=1,fh=1;
    double sum=0,x,fm=0;
    while(i<=100){
        i++;
        fm=fm+1;        
        x=fh*1/fm;
        fh=-fh;
        sum=sum+x;                
    }
    printf("sum=%lf",sum);
    return 0;
}

#include<stdio.h>
int main()
{
    int i=1,fh=1;
    double sum=0,x,fm=0;
    do{
        i++;
        fm=fm+1;        
        x=fh*1/fm;
        fh=-fh;
        sum=sum+x;                
    }while(i<=100);
    printf("sum=%f",sum);
    return 0;
}

#include<stdio.h>
int main()
{
    int i,fh=1;
    double sum=0,x,fm=0;
    for(i=1;i<=100;i++){
        fm=fm+1;
        x=fh*1/fm;
        fh=-fh;
        sum=sum+x;        
    }
    printf("sum=%lf",sum);
    return 0;
}

#include<stdio.h>
int main()
{
    double sum1=1,sum2=0,i;
    while(i<10){        
        i++;
        sum1=sum1*i;
        printf("%.0lf!=%.0lf\n",i,sum1);        
        sum2=sum2+sum1;
    }
    printf("1!+2!+...+10!=%.0lf",sum2);
    return 0;
}

#include<stdio.h>
int main()
{
    int x1=1,x2=1,i=1;
    printf("1,1,");
    while(i<=4){
    i++;
    x1=x1+x2;
    x2=x2+x1;
    printf("%d,%d,",x1,x2);
    }
    return 0;
}

#include<stdio.h>
int main()
{
    int i,x1,x2,x;
    x1=1,x2=1;
    printf("%3d%3d",x1,x2);
    for(i=1;i<=8;i++){
        x=x1+x2;
        printf("%3d",x);
        x1=x2;
        x2=x;
    }
    return 0;
}

#include<stdio.h>
int 
main()
{
    double n,x1,x2,x3,i=1,sum=0,item;
    printf("Input n:\nn=");
    scanf("%lf",&n);
    scanf("%lf%lf",&x1,&x2);
    while(i<=n){
        i++;
        item=x1/x2;
        x3=x1;
        x1=x1+x2;
        x2=x3;
        sum=sum+item;
    }
    printf("sum=%.2lf",sum);
    return 0;
} 

#include<stdio.h>
int main()
{
    double sum=0,a,n,i=1,b;
    printf("Input a,n:");
    scanf("%lf%lf",&a,&n);
    b=a;
    while(i<=n){
        i++;        
        sum=sum+a;                
        a=10*a+b;    
    }
    printf("sum=%lf",sum);
    return 0;
}