2、dio.h>main(){floatr,s,l;printf("pleaseinputr:");scanf("%f”,&r);if(r>=0){s=pi*r*r;l=2*i*r;printf("theareais%f",s);printf("thecircumferenceis%f",l);}elseprintf("inputerror!");}3、函数y=f(x)可表示为:2x+1(x<0)y=0(x=0)2x-1(x>0)编程实现输入一个x值,输出y值。main(){intx,y;scanf(
3、“%d”,&x);If(x<0)y=2*x+1;If(x>0)y=2*x-1;If(x==0)y=0;printf(“%d”,y);}20计算机程序设计基础(c语言)习题编程题4、编写一个程序,从4个整数中找出最小的数,并显示此数。main(){inta,b,c,d,t;scanf(“%d,%d,%d,%d”,&a,&b,&c,&d);if(a>b){t=a;a=b;b=t;}if(a>c){t=a;a=c;c=t;}if(a>d){t=a;a=d;d=t;}printf(“min=%d”,a);}5.有一函
4、数当x<0时y=1,当x>0时,y=3,当x=0时y=5,编程,从键盘输入一个x值,输出y值。main(){intx,y;scanf("%d",&x);if(x<0)y=1;elseif(x==0)y=5;elsey=3;printf("x=%d,y=%d",x,y);}6.从键盘输入两个数,求出其最大值(要求使用函数完成求最大值,并在主函数中调用该函数)main(){floatmax(floatx,floaty);floata,b,m;scanf("%f,%f",&a,&b);m=max(a,b);prin
5、tf("Maxis%f",m);}floatmax(floatx,floaty){floattemp;if(xmain(){intyourAge,hisAge;printf("Pleaseenteryourage:");scanf("%d",&yourAge);/*输入你的年龄yourAge*/
6、printf("Pleaseenteryourfriend'sage:");scanf("%d",&hisAge);/*输入你朋友的年龄hisAge*/if(yourAge>=hisAge) {printf("Youareolder!Yourageis=%d",yourAge); }if(hisAge>yourAge) {printf("Yourfriendisolder!HisAgeageis=%d",hisAge); }}8、键盘输入2个加数,再输入答案,如果正确,显示“right”,否则显示“err
7、or”#include“stdio.h”main(){inta,b,c;printf(“pleaseinputaandb”);scanf(%d,%d”,&a,&b);printf(“pleaseinputtheanswerfora+b”);scanf(%d”,&c);if(c==a+b)printf(“right”);elseprintf(“error”);}9.编一程序每个月根据每个月上网时间计算上网费用,计算方法如下:要求当输入每月上网小时数,显示该月总的上网费用(6分)main(){inth
8、our;floatfee;printf(“pleaseinputhour:”);20计算机程序设计基础(c语言)习题编程题scanf(“%d”,&hour);if(hour<=10)fee=30;elseif(hour>=10&&hour<=50)fee=3*hour;elsefee=hour*2.5;printf(“Thetotalfeeis%f”,fee);}10