第一次实验课

#include<stdio.h>
int main()
{
    int x, y;
    int r1, r2, r3, r4;
    x = 1;
    y = 2;
    r1 = x + y;
    r2 = x - y;
    r3 = x * y;
    r4 = x / y;
    printf("r1 = %d\n", r1);
    printf("r2 = %d\n", r2);
    printf("r3 = %d\n", r3);
    printf("r4 = %d\n", r4);
    return 0;
    
    
}

#include<stdio.h>
int main()
{
    float x, y;
    float r1, r2, r3, r4;
    x = 1;
    y = 2;
    r1 = x + y;
    r2 = x - y;
    r3 = x * y;
    r4 = x / y;
    printf("r1 = %f\n", r1);
    printf("r2 = %f\n", r2);
    printf("r3 = %f\n", r3);
    printf("r4 = %f\n", r4);
    return 0;
    
    
}

#include<stdio.h>
int main()
{
    
    int n, r1, r2, r3, r4;
    n = 100;
    r1 = n*(n+1)/2;
    r2 = (n+1)*n/2;
    r3 = n/2*(n+1);
    r4 = (n+1)/2*n;
    printf("n = %d\n", n);
    printf("r1 = %d\n", r1);
    printf("r2 = %d\n", r2);
    printf("r3 = %d\n", r3);
    printf("r4 = %d\n", r4);
    return 0;
    
    
}

#include<stdio.h>
int main()
{int answer;
 char words[5000];
 
 printf("网课让一些人欢喜一些人忧.\n");
 printf("1.作为一个宅，社恐，觉得这样很好.有网络，自主学习，很ok.\n");
 printf("2.不喜，不喜，很不喜.眼睛快瞎了.脑壳有点卡...\n");
 printf("3.中间派.不知道.说不清.\n");
 printf("你的选择：");
 scanf("%d", &answer);
 if(answer == 4){
     printf("请补充说明你的想法：\n");
     getchar();
     gets(words);
     
     
 }
 printf("\n");
 printf("当遇到问题时，你会选择：\n");
 printf("1. 遇到问题，就解决问题。不懂的，搜索式学习，逐个攻破.\n");
 printf("2. 遇到问题，不高兴。然后.....没有了.\n");
 printf("3. 其他...\n");
 printf("你的选择：");
 scanf("%d", &answer);
 
 if(answer == 1)
 printf(":)\n");
 else if(answer == 2)
 printf("这样不能解决问题啊...我们选1好不好:)\n");
 else if(answer == 3){
     printf("请补充你的想法：\n");
     getchar();
     gets(words);
 }
 return 0;
 
 
 
  


}
    
    

#include<stdio.h>
int main()
{
    printf(" o \n");
    printf("<H>\n");
    printf("I I\n");
    return 0;
    
 }