exp+3

# include<stdio.h>
# include<stdlib.h>
# include<math.h> 
int main(){
    float a,b,c,x1,x2;
    float delta,real,imag;
    
    printf("请输入a,b,c:");
    
    while(scanf("%f%f%f",&a,&b,&c)!=EOF){
        if (a==0)
        printf("not quadratic equation.\n\n");
        else{
            delta=b*b-4*a*c;
            
            if(delta>=0){
                x1=(-b+sqrt(delta)/(2*a));
                x2=(-b-sqrt(delta)/(2*a));
                printf("x1=%.2f,x2=%.2f\n\n",x1,x2);
                }
        else{
            real=-b/(2*a);
            imag=sqrt(-delta)/(2*a);
            printf("x1=%.2f+%.2fi,x2=%.2f-%.2fi\n\n",real,imag,real,imag);
            }
    }
        printf("entera,b,c:");
}
    return 0 ;
}

 

实验二

# include<stdio.h>
# include<stdlib.h>
# include<time.h>
# define N 10
int main(){
    int x,n;
    
    srand(time(0));
    n=0;
    do{
    n++;
    x=rand()%10;
    printf("%3d",x);
    }while(n<N);
    
    printf("\n");
    
    return 0;
    
} 

 

实验三

# include <stdio.h>
# include <math.h>
int main(){
    int i,m,n,count;
    count=0;
    
    for(m=101;m<=200;m++){
    n=sqrt(m);
    for(i=2;i<=n;i++){
        if(m%i==0)break;
    }
    
    if(i>n){
        printf("%6d",m);
        count++;
        if (count%5==0)
        printf("\n");
    }    
    }
    printf("\n101~200间有%d个素数.",count);
    return 0;
}

 本来还在想怎么把阵列套进去，最后发现定义的计素数个数的count可以直接执行除5取余，判断是否满足0再换行的功能，一举两得，nb。

 

实验四

 

# include<stdio.h>
# include<math.h>
int main(){
    long x,y,z;
    while(printf("Enter a biiiiiiiig number:"),scanf("%ld",&x)!=EOF){
        long i=0,z=0;    
        while(x>0){
            y=x%10;
            if(y%2!=0){
            z+=y*pow(10,i);
            i++;    
            }
            x=x/10;
        }
        printf("neeeeeeeew number is:%ld\n",z);
    }
    return 0;
} 

 

 

x：原长整形数。y：余数。z：新数 i：次幂

算法：x除10取余，得到的y除2取余判断是否为奇数。通过后用i次幂累积高位到低位的数，得出新数。

实验五

#include <stdio.h>
#include <math.h>
int main(){
    int m,n;
    float s;
    printf("Enter n(1~10):");
    while(scanf("%d",&n)!=EOF){
        float s=0,i=1;
        for(m=1;m<=n;m++){
            i=i*m;
            s=s+pow(-1,m-1)*(1/i);
        }
        printf("n=%d,s=%f\n",n,s);
        printf("Enter n(1~10):");
    }
     return 0;         
}

 

实验六

# include<stdio.h>
# include<stdlib.h>
# include<time.h>
int main(){
    int date,answer,count;
    srand((unsigned)time(NULL));
    date= rand()% 31;
    printf("guess guess 0202年哪一天会是你的unlucky day\n");
    printf("开始咯，你居然有三次机会！猜吧（1~31）:");
    
    while (count<3){
        scanf("%d",&answer);
        if(date==answer){
        printf("这就对了？\n");break;}
        else if(date>answer){
        printf("猜的也太小气了吧！？\n");}
        else{
        printf("猜的也太大气了吧！？\n");}
        count++;
    }
    if(count>=3)
    printf("你无了，回复TD退订\n");
    return 0; 
    
}