简单易懂的C语言源代码(供初学者使用)

#include

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

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);

else

printf("shu ru cuo wu!\n");

getch();

}

#include

#include

#include

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

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

#include

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

#include

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

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

#include

#include

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");

else

printf("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

#include

#include

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

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

#include

#include

#include

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

{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");

else

printf("The result is not correct!\n");

i++;}

getch();

}

#include

#include

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");

else

printf("y bu shi run nian !\n");

}

else

printf("y shi run nian!\n");

}

else

printf("y bu shi run nian!");

i++;

}

getche();

}

#include

#include

#include

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");

else

strcpy(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"); else

strcpy(s2,"");

hour1=timeptr->tm_hour;

if(hour1>=4&&hour1<=10) strcpy(s3,"Good morning!"); else if(hour1>=17&&hour1<=22) strcpy(s3,"Good afternoon!"); else

strcpy(s3,"Good evening!"); printf("%s%s%s",s1,s2,s3); getch();

}

#include

#include

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(); }

}