## 实验3 选择结构程序设计 ### 实验任务 3-1.c 运行结果截图：结果1：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210408-1617861820914) 结果2： ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210408-1617861850861) 3-2.c 运行结果截图：结果1：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210408-1617862190343) 结果2：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210408-1617862203268) 3-3.c 运行结果截图：有折扣的运行结果：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618409658595) 无折扣的运行结果：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618409623120) 3-4.c 运行结果截图：结果1：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618411137544) 结果2：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618411149578) ### 上机练习 1、输入一个整数，输出它的绝对值。 - 方法1的代码 ``` ``` ```c ##include #include int main(int argc,const char **argv) { int number = 0; scanf("%d",&number); printf("|%d|=%lf ",number,fabs(number)); return 0; } ``` - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618412770572) - - 方法2的代码 ```c ##include int main() { float a; printf("qing shu ru yi ge zheng shu:"); scanf("%f",&a); if(a>=0) printf("%f",a); else printf("%f",-a); return; } ``` - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618413273418) 2、输入一个字符，判断该字符是否是数字，若为数字，输出1，否则输出0。 - 代码 ```c ##include int main(void) { char a; printf(" ????????"); scanf("%c",&a); if(a>='0'&&a<='9') printf("1 "); else printf("0 "); return; } ``` - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618413541889) 3、 [课后题3]，至少用两种方法实现，对比思考哪一种方法更好一些？ - 多分支方法实现的代码 ```c ##include int main() { int x; printf("????????"); scanf("%d",&x); if(x<0) printf("0 "); else if(x<10) printf("x "); else if(x<20) printf("x+1 "); else if(x<30) printf("2x-1 "); else printf("3x+1 "); return 0; } ``` - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618413857777) - if嵌套方法实现的代码 ```c ##include int main() { int x,y; scanf("%d",&x); if(x<0) y=0; else if(x>=0&&x<10) { y=x; } else if(x>=10&&x<20) { y=x+1; } else if(x>=20&&x<30) { y=2*x-1; } else { y=3*x+1; } printf("y=%d ",y); return 0; } ``` - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618414313327) - 哪一种方法更好：第二种 4、 [课后题3]，至少用两种方法实现，对比思考哪一种方法更好一些？ - 任务一：练习PPT中最后一页里的菜谱题目，利用数字1-7表示的代码 ```c ##include int main() { int a; printf("input integer nmber:"); scanf("%d",&a); switch(a) { case1:printf("Monday青菜\n");break; case2:printf("Tuesday鸡\n");break; case3:printf("wednesday鱼\n");break; case4:printf("Thurday肉\n");break; case5:printf("Friday蛋\n");break; case6:printf("Saturday豆制品\n");break; case7:printf("Sunday海鲜\n");break; default:printf("error"); } return 0; } ``` - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210414-1618415184736) - 任务二：[课后题4]输入星期首字母，判断星期几，当遇到S或T时，需要再输入一个字母，从而判断出准确日期的代码 ```c ##include int amin() { char letter; printf("qing shu ru xing qi ji de di yi ge zi mu:"); letter = getchar(); //while(printf("?????????????")&&((letter = getchar())!=?Y?); //{ switch(letter) { case 'M': printf("Monday:??? "); break; case 'T': printf("?????????"); if((letter=getchar())=='u') { printf("Tuesday:??? "); break; } else if((letter=getchar())=='h') { printf("Thursday???? "); break; } else { printf("T???????????? "); break; } case 'W': printf("Wednesday:??? "); break; case 'F': printf("Friday:??? "); break; case 'S': printf("?????????"); if((letter = getchar())=='a') { printf("Saturday:??? "); break; } else if((letter = getchar())=='u') { printf("Sunday:??? "); break; } else { printf("S???????????? "); break; } default: printf("???????? "); break; } return 0; } ``` - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1527890-20210415-1618417029682)

“程序设计基础II”实验报告