1、从键盘输入圆的半径R，计算并输出圆的周长和面积。
#include <stdio.h>
#define PI 3.1415926
void main()
{
float
r,l,s;
printf("Please input r = ");
scanf("%f",&r);
l=2*PI*r;
s=PI*r*r;
printf("l
= %f\n",l);
printf("s =
%f\n",s);
getch();
}
2、从键盘输入任意一个十六进制的负整数，以输入的形式输出。例如：输入-FA98，输出-FA98。
#include
<stdio.h>
void main ( )
{
int a;
printf("Please input
16bit:a = ");
scanf("-%X",&a);
printf("a = -%X\n",a);
getch();
}
3、已知一元二次方程ax2+bx+c=0,编一程序当从键盘输入a,b,c的值后，计算X的值。
#include <stdio.h>
void main()
{
float
a,b,c,x1,x2;
printf("Please input a,b,c.\n");
printf("a =
",a);
fflush(stdin);
scanf("%f",&a);
printf("b
= ",b);
fflush(stdin);
scanf("%f",&b);
printf("c
= ",c);
fflush(stdin);
scanf("%f",&c);
printf("result:%fx^2+%fx+%f.\n",a,b,c);
if
((b*b-4*a*c)>0){
x1=(-b+sqrt(b*b-4*a*c))/(2*a);
x2=(-b-sqrt(b*b-4*a*c))/(2*a);
printf("difference:\nx1 = %f \nx2 = %f\n",x1,x2);
}
else if
((b*b-4*a*c)==0){
x1=-b/(2*a);
printf("same:'nx1 = x2 = %f\n",x1);
}
else
if((b*b-4*a*c)<0){
x1=b/(2*a);
x2=sqrt(4*a*c-b*b)/(2*a);
printf("another:\nx1 = %f \nx2 = %f",x1,x2);
}
else
printf("OK\n");
getch();
}
暂时完成这样，可以运行，这是在TC下编辑的。
修改:
#include <stdio.h>
#include <math.h>
void main()
{
double a,b,c,x1,x2;
printf("请输入a,b,c: \n");
printf("a = ");
scanf("%lf",&a);
printf("a = %lf\n",a);
printf("b = ");
scanf("%lf",&b);
printf("b = %lf\n",b);
printf("c = ");
scanf("%lf",&c);
printf("c = %lf\n",c);
printf("sss:%lfx^2+%lfx+%lf=0\n",a,b,c);
if((b*b-4*a*c)>0){
x1=(-b+sqrt(b*b-4*a*c))/(2*a);
x2=(-b-sqrt(b*b-4*a*c))/(2*a);
printf("有两个不同的根:\nx1 = %f \nx2 = %f\n",x1,x2);
}
else if ((b*b-4*a*c)==0){
x1=-b/(2*a);
printf("相同的根:'nx1 = x2 = %f\n",x1);
}
else
if((b*b-4*a*c)<0){
x1=b/(2*a);
x2=sqrt(4*a*c-b*b)*(1/2)/(2*a);
printf("异同:\nx1 = %f \nx2 = %f\n",x1,x2);
}
else printf("ok\n");
}
4、编一程序判断输入整数的正负性和奇偶性。
#include <stdio.h>
void main()
{
int a;
printf("输入整数a : ");
scanf("%d",&a);
if (a>0){
if(a%2==0)
printf("a =
%+d a是偶数\n",a);
else
printf("a =
%+d a是奇数\n",a);
}
else if(a==0){
printf("a = %d
a是零\n",a);
}
else if(a<0){
if(a%2==0)
printf("a =
%+d a是偶数\n",a);
else
printf("a =
%+d a是奇数\n",a);
}
else printf("您输入错误");
}
5、编程判断输入数据的符号属性。sign=1
x>0
sign=0
x=0
sign=-1
x<0
输入x，打印出sign的值。
#include <stdio.h>
void main()
{
int x;
printf("请输入x = ");
scanf("%d",&x);
if(x>0)
printf("sign = 1\n");
else if(x==0)
printf("sign = 0\n");
else if(x<0)
printf("sign = -1\n");
else
printf("输入错误!");
}
6、输入任意三个数num1,num2,num3,按从小到大的顺序排序输出。
#include <stdio.h>
void main()
{
int num1,num2,num3;
printf("请输入三个数\nnum1 = ");
scanf("%d",&num1);
printf("num2 = ");
scanf("%d",&num2);
printf("num3 = ");
scanf("%d",&num3);
if(num1>num2){
if(num3>num1)
printf("%d
%d %d\n",num3,num1,num2);
else
if(num3<num1){
if(num3>num2)
printf("%d
%d %d\n",num1,num3,num2);
else
if(num3<num2)
printf("%d
%d %d\n",num1,num2,num3);
}
}
else if(num2>num1){
if(num3>num2)
printf("%d
%d %d\n",num3,num2,num1);
else
if(num3<num2){
if(num3>num1)
printf("%d
%d %d\n",num2,num3,num1);
else
if(num3<num1)
printf("%d
%d %d\n",num2,num1,num3);
}
}
}
7、在屏幕上显示一张如下所示的时间表：
******Time******
1
morning
2
afternoon
3 night
Please enter your choice;
操作人员根据提示进行选择，程序根据输入的时间序号显示相应的问候信息，选择1时显示"Good morning",选择2时显示"Good
afternoon",选择3时显示"Good night",对于其他的选择显示"Selection
error!"，用switch语句编程实现。
#include <stdio.h>
void main()
{
int a;
printf("******Time******\n1
morning\n2
afternoon\n3
night\nPlease enter your choice;\n");
scanf("%d",&a);
switch(a){
case 1:
printf("Good morning\n");
break;
case 2:
printf("Good
afternoon\n");
break;
case 3:
printf("Good night\n");
break;
default:
printf("Selection
error!\n");
break;
}
}
8、输入一个年份和月份，打印出该月份有多少天（考虑闰年），用switch语句编程。
#include <stdio.h>
void main()
{
int year,month;
printf("请输入年份和月份\nyear = ");
scanf("%d",&year);
printf("请输入月份\nmonth = ");
scanf("%d",&month);
if(year!=0){
if((year%4==0)&&(year%100==0)||(year%400==0)){
printf("您输入的年份是闰年!\n");
switch(month){
case
1:
case
3:
case
5:
case
7:
case
8:
case
10:
case
12:
printf("date
= 31天\n");
break;
case
2:
printf("date
= 29天\n");
break;
case
4:
case
6:
case
9:
case
11:
printf("date
= 30天\n");
break;
default:
printf("error");
break;
}
}
else{
printf("您输入的年份不是闰年!\n");
switch(month){
case
1:
case
3:
case
5:
case
7:
case
8:
case
10:
case
12:
printf("date
= 31天\n");
break;
case
2:
printf("date
= 28天\n");
break;
case
4:
case
6:
case
9:
case
11:
printf("date
= 30天\n");
break;
default:
printf("error");
break;
}
}
}
}
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