实验2 C语言分支与循环基础应用编程-1

任务一

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 5
#define N1 397
#define N2 476
#define N3 21

int main() {
    int cnt;
    int random_major, random_no;

    srand(time(NULL));      // 以当前系统时间作为随机种子

    cnt = 0;
    while(cnt < N) {
        random_major = rand() % 2;

        if(random_major) {
            random_no = rand() % (N2 - N1 + 1) + N1;
            printf("20248329%04d\n", random_no);
        }
        else {
            random_no = rand() % N3 + 1;
            printf("20248395%04d\n", random_no);
        }

        cnt++;
    }

    return 0;
}

 第二十一行的作用是生成397到476之间的随机数作为学号后缀

第二十五行的作用是生成1到21之间的随机数作为学号后缀

本程序功能为首先根据系统时间生成随机数种子，再生成随机数，若为奇数，则为20248329前缀的学号随机生成397到476之间的后缀，接着补0输出，若为偶数，则为20248395前缀的学号生成1到21之间的后缀，补0输出，上述流程共重复5次，共打印五行学号

任务二

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

int main() {
    double a, b, c;
    double delta, p1, p2; 

    while(scanf("%lf%lf%lf", &a, &b, &c) != EOF) {
        if(a == 0) {
            printf("a = 0, invalid input\n");
            continue;
        }

        delta = b*b - 4*a*c;
        p1 = -b/2/a;
        p2 = sqrt(fabs(delta))/2/a;

        if(delta == 0)
            printf("x1 = x2 = %.2g\n", p1);
        else if(delta > 0)
            printf("x1 = %.2g, x2 = %.2g\n", p1+p2, p1-p2);
        else {
            printf("x1 = %.2g + %.2gi, ", p1, p2);
            printf("x2 = %.2g - %.2gi\n", p1, p2);
        }
    }

    return 0;
}

任务三

#include<stdio.h>
int main(){
    char a;
    while(scanf("%s",&a)!=EOF){
        if(a=='y'){
            printf("wait a minute\n");
        }
        else if(a=='r'){
            printf("stop!\n");
        }
        else if(a=='g'){
            printf("go go go\n");
        }
        else{
            printf("something must be wrong...\n");
        }
    }
    return 0;
} 

 任务四

#include <stdio.h>
int main(){
    printf("输入今日开销，直到输入-1终止\n");
    double money,sum=0,maxn=0,minn=1e10;
    while(scanf("%lf",&money) && (money!=-1)){
        if(money>maxn){
            maxn=money;
        }
        if(money<minn){
            minn=money;
        }
        sum+=money;
        
    }
    printf("今日累计消费总额：%.1f\n",sum);
    printf("今日最高一笔开销：%.1f\n",maxn);
    printf("今日最低一笔开销:%.1f\n",minn);
    return 0; 
}

任务五

#include <stdio.h>

int main() {
    int a, b, c;

    while (scanf("%d %d %d", &a, &b, &c) == 3) {
        if (a + b <= c || a + c <= b || b + c <= a) {
            printf("不能构成三角形\n");
        } else {
            if (a == b && b == c) {
                printf("等边三角形\n");
            } else if (a == b || a == c || b == c) {
                printf("等腰三角形\n");
            } else {
                int max_side = a;
                if (b > max_side) max_side = b;
                if (c > max_side) max_side = c;

                if (max_side == a) {
                    if (b * b + c * c == a * a) {
                        printf("直角三角形\n");
                    } else {
                        printf("普通三角形\n");
                    }
                } else if (max_side == b) {
                    if (a * a + c * c == b * b) {
                        printf("直角三角形\n");
                    } else {
                        printf("普通三角形\n");
                    }
                } else {
                    if (a * a + b * b == c * c) {
                        printf("直角三角形\n");
                    } else {
                        printf("普通三角形\n");
                    }
                }
            }
        }
    }

    return 0;
}

 任务六

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

int main() {
    int lucky_day, guess;
    int attempts = 3;
    srand(time(NULL));
    lucky_day = rand() % 30 + 1;

    printf("欢迎来到猜日期游戏！请猜测11月的幸运日（1到30）:\n");

    while (attempts > 0) {
        printf("你还有 %d 次机会。请输入你的猜测: ", attempts);
        scanf("%d", &guess);

        if (guess < 1 || guess > 30) {
            printf("请输入一个有效的日期（1到30之间）！\n");
            continue;
        }

        if (guess == lucky_day) {
            printf("恭喜你，猜对了！\n");
            return 0; 
        } else if (guess < lucky_day) {
            printf("你猜的日期太早了。\n");
        } else {
            printf("你猜的日期太晚了。\n");
        }

        attempts--;
    }

    printf("很遗憾，你没有猜中。11月的幸运日是 %d。\n", lucky_day);
    
    return 0;
}