实验三

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 5

int main() {
    int x, n; 
    
    srand(time(0)); 
    
    for(n=1; n<=N; n++) {
        x = rand() % 100;  
        printf("%3d", x);
    }
    
    printf("\n");
    
    return 0;
} 

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(){
    int x,y;
    int n=1;
    srand(time(0));
    x=rand()%32;
    printf("开始喽，你有三次机会，猜吧（1~31）：");
    
    for(;n<=3;n++){
        scanf("%d",&y);
        if(y>x){
            printf("你猜的日期晚了，luck day悄悄溜到前面啦"); 
            if(n!=3){
                printf("\n再猜（1~31）");
            }
            else{
                printf("\n");
            }
        }
        else if(y<x){
            printf("luck day还没到呢"); 
            if(n!=3){
                printf("\n再猜（1~31）");
        }
            else{
                printf("\n");
        }
        }
        else if(y=x){
            printf("恭喜你，猜对了！");
            return 0; 
        }
        
        
    }
    printf("\n次数用完啦。偷偷告诉你：5月，你的luck day是%d",x);
    return 0;
}

#include <stdio.h>
int main(){
    long long s;
    int t=0;
    int n=1;
    int x=1;
    printf("Enter a number:");
    while(scanf("%lld",&s) != EOF){
    int y=0;
    while(s!=0){
        n=s%10;
        s=(s-n)/10;
        if(n%2!=0)
        t=t*10+n;
        }
    while(t!=0){
        x=t%10;
        t=(t-x)/10;
        y=y*10+x;
    }
    printf("new number is:%d\nEnter a number:",y);
    }
    return 0;
} 

#include <math.h>
#include <stdio.h>

void solve(double a, double b, double c);


int main(){
    double a,b,c;
    
    printf("Enter a,b,c:");
    while(scanf("%lf%lf%lf",&a,&b,&c) != EOF){
        solve(a,b,c);
        printf("Enter a,b,c:");
    }
    
    return 0;
}



void solve(double a, double b, double c){
    double x1, x2;
    double delta, real, imag;
    
    if(a == 0)
        printf("not quadratic equation.\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",x1,x2); 
        }
        else{
            real=-b/(2*a);
            imag=sqrt(-delta)/(2*a);
            printf("x1=%.2f+%.2fi,x2 = %.2f-%.2fi\n",real,imag,real,imag);
               }
    }
}

#include <stdio.h>
double fun(int n); // 函数声明

int main() {
int n;
double s;
printf("Enter n(1~10): ");
while(scanf("%d", &n) != EOF) {
s = fun(n); // 函数调用
printf("n = %d, s= %f\n\n", n, s);
printf("Enter n(1~10): ");
}
return 0;
}
// 函数定义
double fun(int n) {
double x;
int i=1,y=1;
double t=0;
    for(i=1;i<=n;i++){
        y=i*y;
        if(i%2==0)
            x=(-1/(double)y);
        else
            x=(1/(double)y);
    t=t+x;
    }
    return t;
}

#include <stdio.h>
#include <math.h>
int isPrime(int n); 
int main(){
    int n,i,m,a,t=0;
    printf("获得两数之间的素数\n请输入两数：\n"); 
    scanf("%d%d",&i,&n);
    a=i;
    for(;i<=n;i++){
        m=isPrime(i);
        if(m!=0&&m!=1){
        printf("%d ",m); 
        t=t+1;
        if(t%5==0)
        printf("\n");}}
    printf("\n\n%d^%d之间素数个数为：%d",a,n,t);
    return 0;
}

int isPrime(int n){
    int x,result;
    int y=2;
    x=sqrt(n);
    while(y<=x&&n%y!=0){
        y=y+1;
    }
    if(y>x)
    return n;
    else
    return 0;
}