实验1 C语言开发环境使用和数据类型、运算符、表达式

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

  return 0;}

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

  return 0;}

#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 = %d\n", r1);
     printf("r2 = %d\n", r2);
     printf("r3 = %d\n", r3);
     printf("r4 = %d\n", r4);
  return 0;}

r4值不同的原因：更改了x，y的数据类型

#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;}

理论上分析r1,r2,r3,r4的值都应该为5050

#include <stdio.h>
int main(){
     int n, r1, r2, r3, r4;
     
     n = 101;
     
     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;}

理论上分析r1,r2,r3,r4值为5151

对应的数学计算式分别为

r1= n*(n+1)/2

r2=(n+1）*n/2

r3=[n/2]*(n+1)

r4=[(n+1)/2]*n

实际上第一次运行中r4的值为5000，这是因为r4的数据类型为整型，所以（n+1）/2得到的结果为50而不是51   ,同理，第二次运算，r3的值为5100，与r1,r2结果不同

 

#include <stdio.h>
int main(){
   int answer;
   char words[5000];
   
   printf("网课学习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("4. 其他...\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。不懂得，搜索式学习，逐渐解决问题.\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： \n");
   scanf("%d",&answer);
   
   if(answer == 1)
       printf(":)\n");
    else if(answer == 2)
       printf("这不样能解决问题啊...我们选择1好不好：）\n");
    else if(answer == 3){
        printf("请补充说明你的想法：\n");
        getchar();
        gets(words);
        
    }
    
    return 0;
}