实验3

实验1

// 生成N个0~99之间的随机整数，并打印输出 
#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; 
}

 

line 13改为x=rand（）%31+1

实验2

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main()
{
int luckday,x,i;
srand(time(0));
luckday = rand()%31+1;
printf("猜猜2021年5月哪一天会是你的luckday\n开始喽，你有三次机会，猜吧（1~31）:");
for(i=1;i<=3;i++){
    scanf("%d",&x);
    if(x>luckday)
        printf("你猜的日期晚了，luck day 悄悄溜到前面啦\n再猜（1~31）:");
     
    else if(x<luckday)
        printf("你猜的日期早了，luckday还没到呢\n再猜(1~31)");
    else
        break;
}
if(i>3)
    printf("次数用完啦。偷偷告诉你：5月，你的luckday是%d号",luckday);
 
 
    return 0;
}

实验3

#include<stdio.h>
#include<stdlib.h>
int main()
{
    long int s,sum=0;
    int m,i=1,n;
    printf("Enter a number:");
    scanf("%ld",&s);
    do{
        m=s%10;
        s=s/10;
        if(m%2!=0){
            sum+=m*i;
            i*=10;}
        
    }while(s!=0);
printf("new number is:%ld\n",sum);
    
    return 0;
}

实验4

#include<stdio.h>
#include<math.h>
#include<stdlib.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:");
    }
    system("pause");
    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);
        }
    }
}

否

实验5

 

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

实验6

#include<stdio.h>
#include<stdlib.h>
int isPrime(int);
int main(){
    int i=0,x,sign,sum=0;
    for(x=101;x<=200;x++){
        sign=isPrime(x);
        if(sign==0){
            printf(" %d",x);
            i++;
            x++;
            sum++;
            if(sum%5==0){
                printf(" \n");
            }
        }
    }
    printf("\n101~200的素数一共有%d\n",i);
    
     return 0;
}
int isPrime (int x){
    int n=0,i;
    for(i=2;i<x;i++){
        if(x%i==0)
            n++;
    }return n;
}