#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(){
    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(){
    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;
}

 

 int为整型，float为浮点型，float的精度更高

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

 

赋值运算符右侧的表达式对应的数学计算式为“首项加末项乘项数除以2”的求和公式

当n取偶数时，r4中(n+1)/2先计算得到小数，然后舍弃小数用整数部分进行下一步计算，故最终得到的r4会得到不相同的计算结果；同理，当n取奇数时，r3也会得到不相同的计算结果。

 

 

#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愁.\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.其它。。。\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.其它。。。.\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;
}

 

 五：我感受到了C语言的奇妙之处，运行的时候非常期待也非常兴奋，感觉学到了很多知识