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>
#define N 5

int main() {
    int x, n; 
    
    srand(time(0)); 
    
    for(n=1; n<=N; n++) {
        x = rand() % 20;  
        printf("%3d", x);
    }
    
    printf("\n");
    
    return 0;
} 

 

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 3

int main() {
    int x, n,a; 
    
    srand(time(0)); 
    x = rand() % 31+1;  
    printf("猜猜2021年5月哪一天会是你的lucky day\n");
    printf("开始喽，你有三次机会，猜吧(1~31):\n");
    for (n = 1; n <= N;) {
        scanf("%d", &a);
        if (n <= 3) {
            if (a > x) {
                printf("你猜的日期晚了，lucky day悄悄溜到前面了\n");
                if (n < 3) {
                    printf("再猜（1~31）：");
                }
            }
            else if (a < x) {
                printf("你猜的日期早了，lucky day悄悄溜到后面了\n");
                if (n < 3) {
                    printf("再猜（1~31）：");
                }
            }
            else {
                printf("恭喜你猜对了！\n");break;
            }
            n++;
            if (n > 3)
                break;
        }
    }
            printf("次数用完咯，偷偷告诉你：五月，你的幸运日是%d号", x);
    return 0;
} 

 

#include<stdio.h>
int main() {
    long m, n;
    int a, b, N, x, i;
    while (printf("Enter a number:"), scanf_s("%d", &m)!=EOF )
    {
        n = m;
        for (N = 0;n>0;N++) {
            n  /= 10;
        }
        for (x = 0, a = 0, i = 1, b = 0;x<N;x++) {
            a = m % 10;
            m = m / 10;
            if (a % 2) {
                b = b + a*i;
                i = i * 10;
            }
        }
        printf("new number=%d\n\n", b);
    }
    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 s=1,a=1;
    int i;
        if (n == 1)
            return 1;
        else{
            for ( i = 2; i <= n; i++){
                a = -a * 1 / i;
                s = s + a;
            }
            return s;
        }
}

复制代码

 

#include<stdio.h>

int main() {
    
    int x,n=0;

    for (x = 100;x <= 200;x++) {
        int i;
        int isPrime = 1;
        for (i = 2;i < x; i++) {
            if (x%i==0) {
                isPrime = 0;
                break;
            }
        }
        if (isPrime==1){
            n++;
            printf("%d ", x);
            if (n % 5 == 0){
                printf("\n");
            }
        }
    }
    printf("\n100~200之间素数个数为：%d", n);

    return 0;
}