#include <stdio.h>#include <stdlib.h>#include <time.h>#define N 5int main(){    int grade, number;    int i;    srand(time(0));    for (i = 0; i < N; i++)    {        grade = rand() % 4 + 2018;           number = rand() % 999 + 1;           printf("%d8330%04d\n", grade, number);    }    return 0;}

question1.在2018-2021间取随机数

question2.在1-999间取随机数

question3.随机取一个学号

#include<stdio.h>#include<stdlib.h>#include<time.h>int main(){    int x,n,ans;    srand(time(0));    x=rand()%30+1;    printf("猜猜2022年4月哪一天会是你的lucky day\n");    printf("开始喽,你有三次机会,猜吧(1~30):");    for(n=1;n<=3;n++){       scanf("%d",&ans);       if(ans==x){       printf("哇,猜中了");       break;}       else if(ans<x){           printf("你猜的日期早了,你的lucky day还没到呢。");       }           else if(ans>x){               printf("你猜的日期晚了,你的lucky day已经过了。");           }        if(n<=2){               printf("\n再猜(1~30):");           }    }    if(n==4){        printf("\n次数已经用完了,偷偷告诉你你的lucky day是4月%d号",x);    }    return 0;}

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

#include <stdio.h>#include <math.h>int main(){    int i,n,a;    printf("n=?,a=?\n");    while(scanf("%d%d",&n,&a)!= EOF)    {        float d=0.0,s=0.0;        for(i=1;i<=n;i++)        {            d+=a*pow(10,i-1);            s+=i/d;        }        printf("n = %d, a = %d, s= %f\n",n,a,s);        printf("n=?,a=?\n");    }    return 0;}

#include <stdio.h>int main(){    int column,line;    for(column=1;column<=9;column++)    {        for(line=1;line<=column;line++)        {            printf("%dx%d=%2d ",line,column,line*column);        }        printf("\n");    }    return 0;}

#include <stdio.h>int main(){    int j,i;    printf("input n:");    scanf("%d",&i);    for(j=1;j<=i;j++)    {        printf(" o \n");        printf("<H>\n");        printf("I I\n\n");    }    return 0; }

#include <stdio.h>int main(){    int i,j;    printf("input n:");    scanf("%d",&i);    for(j=1;j<=i;j++)    {        printf(" o   ");    }    printf("\n");    for(j=1;j<=i;j++)    {        printf("<H>  ");    }    printf("\n");    for(j=1;j<=i;j++)    {        printf("I I  ");    }    printf("\n");    return 0;}

#include<stdio.h>int main(){    int N,m,n,a;    printf("input n:");    scanf("%d", &N);    for (m = 1; m <= N; m++)    {        for (n = 0; n <= m; n++)            printf("\t");        for (a = 0; a < N * 2 + 1 - m * 2; a++)            printf(" o \t");            printf("\n");        for (n = 0; n <= m; n++)            printf("\t");        for (a = 0; a < N * 2 + 1 - m * 2; a++)            printf("<H>\t");            printf("\n");        for (n = 0; n <= m; n++)            printf("\t");        for (a = 0; a < N * 2 + 1 - m * 2; a++)            printf("I I\t");            printf("\n");    }    return 0; }