3-1.c 运行结果截图：结果1：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618574680236) 结果2：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618574738264) 3-2.c 运行结果截图：结果1：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618574970537) 结果2![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618574989088)： 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/uid1535518-20210416-1618575099440) 无折扣的运行结果：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618575112663) 3-4.c 运行结果截图：结果1：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618575630380) 结果2：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618575642663) ### 上机练习 1、输入一个整数，输出它的绝对值。 - 方法1的代码 int main( ) { int a,b; printf("input a int:"); scanf("%d",&a); b = fabs(a); printf("it is :%d",b); return 0; } - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618575957426) - - 方法2的代码 int main( ) { int a,b; printf("input a int:"); scanf("%d",&a); if(a>=0) printf("it is:%d",a); else { b = -a; printf("it is :%d",b); } return 0; } - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618576096555) 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 int main( ) { char a; printf("shu ru yi ge zifu:"); scanf("%c",&a); if(a<65) printf("%d",a<65); else printf("%d",a<65); return 0; } - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618576263977) 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 int main( ) { int a,b; printf("input X:"); scanf("%d",&a); if(a<0) { b=0; printf("X = %d,Y = %d",a,b); } else if(a<10) { b=a; printf("X = %d,Y = %d",a,b); } else if(a<20) { b = a +1; printf("X = %d,Y = %d",a,b);} else if(a<30) { b= 2*a-1; printf("X = %d,Y = %d",a,b);} else { b = 3*a+1; printf("X = %d,Y = %d",a,b); } return 0; } - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618576459328) - if嵌套方法实现的代码 int main( ) { int a,b; printf("input X:"); scanf("%d",&a); if(a<0) { b=0; printf("X = %d,Y = %d",a,b); } else if(a<10) { b=a; printf("X = %d,Y = %d",a,b); } else if(a<20) { b = a +1; printf("X = %d,Y = %d",a,b);} else if(a<30) { b= 2*a-1; printf("X = %d,Y = %d",a,b);} else { b = 3*a+1; printf("X = %d,Y = %d",a,b); } return 0; } - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618576556661) - 哪一种方法更好： 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 int main() { int a; printf("input 1-7,show menu:"); scanf("%d",&a); switch (a) {case 1:printf("青菜\n"); break; case 2:printf("鸡\n"); break; case 3:printf("鱼\n"); break; case 4:printf("肉\n"); break; case 5:printf("鸡蛋\n"); break; case 6:printf("豆制品\n"); break; case 7:printf("海鲜\n"); break; } - 运行结果截图：![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1535518-20210416-1618577418027)

“程序设计基础II”实验报告