#include<stdio.h>main(){float pi=3.14159265,r;printf("enter radius:\n");scanf("%f",&r);printf("r=%.2f,c=%.2f,area=%.2f\n",r,2*pi*r,pi*r*r);system("pause");}#include<stdio.h>main(){int m,n,x,y;printf("inputm,n:\n");scanf("%d%d",&m,&n);if (n%2==1){printf("error!! n bu shi ji shu!\n",n);return;}/*n在这里不能是奇数*/x=(4*m-n)/2;y=(n-2*m)/2;if((x>=0)&&(y>=0))printf("x=%d,y=%d\n",x,y);elseprintf("shu ru cuo wu!\n");getch();}#include<stdio.h>#include<math.h>#include<stdlib.h>main(){float a,b,C;printf("enter 3number(a,b,C):\n"); scanf("%.2f %.2f %.2f",&a,&b,&C); s=0.5*a*b*sinC;printf("s=%.2f\n",s);system("pause");}#include<stdio.h>main(){int ds,nl,yf;char c;printf("shu ru ds;\n");scanf("%d",&ds);if (ds<14||ds>1184){printf("input error!press any end...\n");scanf("%c",&c);exit(0);}/*输入的数字必须是-14~1184之间*/nl=(ds+115)%100;yf=(ds+115)/100;printf("nl=%d,yf=%d\n",nl,yf);system("pause");}#include<stdio.h>#include<string.h>main(){char s1[100],s2[100],s3[100],s4[100];printf("input a string:\n");gets(s1);strcpy(s1,s2);strcat(s1,"--------------");strcpy(s3,strcat(s1,"--------------"));strcat(strcpy(s3,strcat(s1,"--------------")),s2);strcpy(s4,strcat(strcpy(s3,strcat(s1,"--------------")),s2)); puts(s4);system("pasue");getch();}#include<stdio.h>#include<math.h>main(){float x1,x2,a,b,c;printf("input 3 number(a,b,c):\n"); scanf("%f%f%f",&a,&b,&c);x1=(-b+sqrt(b*b-4*a*c))/(2*a);x2=(-b-sqrt(b*b-4*a*c))/(2*a); printf("x1=%f,X2=%f\n",x1,x2); system("pause");getch();}#include<stdio.h>main(){int a,b,c,t;printf("input 3 number:\n");scanf("%d%d%d",&a,&b,&c);if(a>b){t=a;a=b,b=t;}if(a>c){t=a;a=c;c=t;}if(b>c){t=b;b=c;c=t;}printf("1:%d,2:%d,3:%d\n",a,b,c);system("pause");}#include<stdio.h>#include<stdlib.h>#include<conio.h>main(){float pi=3.14159265,r;textbackground(YELLOW);/* 设置背景色为黄色，注意颜色应该大写，可更改 */ textcolor(RED); /* 设置文件颜色为红色，可更改 */clrscr(); /* 清屏，使设置生效 */printf("enter radius:");scanf("%f",&r);if(r<0)printf("Enter Error!\n");elseprintf("r=%.2f,c=%.2f,area=%.2f\n",r,2*pi*r,pi*r*r);system("pause");/* 暂停，按任一键继续 */#include<stdio.h>#include<math.h>#include<conio.h>main(){float a,b,c,delt,x1,x2,p,q;textcolor(YELLOW);clrscr();printf("Input a b c:\n");scanf("%f%f%f",&a,&b,&c);if(a==0){printf("It's not a quadratic equation!\n"); system("pause");return;}delt=b*b-4*a*c;if(delt>=0){x1=(-b+sqrt(delt))/(2*a);x2=(-b-sqrt(delt))/(2*a);printf("x1=%.3f x2=%.4f\n",x1,x2);}else{p=-b/(2*a);q=sqrt(-delt)/(2*a);printf("p=%.4fq=%.4f\n",p,q);}system("pause");getch();}}#include<stdio.h>main(){float pi=3.14159265,r;int k=0;while(k<=3){printf("enter radius:\n");scanf("%f",&r);printf("r=%.2f,c=%.2f,area=%.2f\n",r,2*pi*r,pi*r*r); printf("press any key to continue\npress esc to exit."); k++;}}#include<stdio.h>#include<stdlib.h>#include<time.h>#include<conio.h>main(){int a,b,c,oper;long limit,i=0;char char1;textcolor(GREEN);/*设置字体颜色为绿色*/clrscr(); /*清屏，是设置生效*/while(i<=3){printf("qing xuan ze jia huo jian(1or2,1:+,2:-\n"); scanf("%d",&oper);printf("Enter max (<10000):\n");scanf("%ld",&limit);srand((unsigned long)time(0));a=rand()*limit/RAND_MAX;b=rand()*limit/RAND_MAX;while((a<b)&&(oper==2)){a=rand()*limit/RAND_MAX;b=rand()*limit/RAND_MAX;}char1=(oper==2?'-':'+');printf("%d%c%d\n",a,char1,b);scanf("%d",&c);if((oper==2&&a-b==c)||(oper!=2&&a+b==c))printf("OK!You are very clever!\n");elseprintf("The result is not correct!\n");i++;}getch();}#include<stdio.h>#include<conio.h>main(){int y,i=0;textcolor(YELLOW);/*天下事无难易之分只有做与不做之别*/ textbackground(GREEN);clrscr();/*清屏，是设置生效*/while(i<=3){printf("Input year:\n");scanf("%d",&y);if(y%4==0){if(y%100==0){if(y%400==0)printf("y shi run nian!\n");elseprintf("y bu shi run nian !\n");}elseprintf("y shi run nian!\n");}elseprintf("y bu shi run nian!");i++;}getche();}#include<stdio.h>#include<time.h>#include<string.h>main(){int xz,wday1,hour1;struct tm *timeptr;time_t secsnow;char s1[30],s2[30],s3[30];printf("input whom do you say to?:\n"); scanf("%d",&xz);if(xz==1)strcpy(s1,"mother");else if(xz==2)strcpy(s1,"father");elsestrcpy(s1,"");time(&secsnow);timeptr=localtime(&secsnow); wday1=timeptr->tm_wday;if(wday1==6)strcpy(s2,"Happy saturday!"); else if(wday1==0)strcpy(s2,"Happy sunday"); elsestrcpy(s2,"");hour1=timeptr->tm_hour;if(hour1>=4&&hour1<=10) strcpy(s3,"Good morning!"); else if(hour1>=17&&hour1<=22) strcpy(s3,"Good afternoon!"); elsestrcpy(s3,"Good evening!"); printf("%s%s%s",s1,s2,s3); getch();}#include<stdio.h>#include<conio.h>main(){int day,year,month,i=0;textbackground(BROWN);clrscr();while(i<=3){printf("Input 2 number:\n");scanf("%d%d",&year,&month);switch(month){case 1:case 3:case 5:case 7:case 8:case 10:case 12: day=31;break;case 4:case 6:case 11:day=30;break;case 2:day=28;if((year%4==0&&year%100!=0)||year%400==0)day=29;break;deflault:printf("Invalid month input!\n");return;}printf("There are%d days in %d.%d\n",day,year,month);i++; getch(); }}。