#include <math.h>
#include <stdio.h>
int main()
{
float a, b, c, x1, x2;
float delta, real, imag;
printf("Enter a, b, c: ");
while(scanf("%f%f%f", &a, &b, &c) != EOF)
{
if(a == 0)
printf("not quadratic equation.\n\n");
else
{
delta = b*b - 4*a*c;
if(delta >= 0)
{
x1 = (-b + sqrt(delta)) / (2*a);
x2 = (-b - sqrt(delta)) / (2*a);
printf("x1 = %.2f, x2 = %.2f\n\n", x1, x2);
}
else
{
real = -b/(2*a);
imag = sqrt(-delta) / (2*a);
printf("x1 = %.2f + %.2fi, x2 = %.2f - %.2fi\n\n", real, imag, real, imag);
}
}
printf("Enter a, b, c: ");
}
return 0;
}
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define N 5
int main(){
int x,n;
srand(time(0));
n=0;
do{
n++;
x=rand()%10;
printf("%3d",x);
}while(n<N);
printf("\n");
return 0;
}
1 #include <stdio.h>
2 #include <math.h>
3 main()
4 {
5 int n,s,i,m;
6 for(n = 101; n <= 200; n ++)
7 {
8 s = sqrt(n);
9 for(i = 2; i <= s; ++ i)
10 {
11 if(n % i == 0)
12 break;
13 if(i == s)
14 {
15 m ++;
16 printf("%d\t",n);
17 if(m % 5 == 0)
18 printf("\n");
19 }
20 }
21
22 }
23 printf("\n101~200之间共有%d个素数.",m);
24 }
1 #include<stdio.h>
2 int main()
3 {
4 long long s,n,m;
5 printf("Enter a number:");
6 scanf("%ld",&s);
7 printf("new number is: ");
8 for(n = 1; s / n != 0; n *= 10 )
9 ;
10 n /= 10;
11 for(; n >= 1; n /= 10)
12 {
13 m = s / n % 10;
14 if(m % 2 == 1)
15 printf("%ld",m);
16 }
17 return 0;
18 }
1 #include <stdio.h>
2 main()
3 {
4 int n,i;
5
6
7 while(scanf("%d",&n) != EOF)
8 {
9 printf("Enter n(1~10): ");
10 double s = 0, t = 1;
11 if(n < 1 || n > 10)
12 printf("Invalid input.");
13 else
14 {
15 for(i = 1; i <= n; i ++, t *= i)
16 {
17 if(i % 2 == 1)
18 s += 1.0 / t;
19 else
20 s -= 1.0 / t;
21 }
22 printf("n = %d, s= %f",n,s);
23 }
24
25 }
26 }
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main(){
int x,y=1,z;
printf("猜猜2020年12月哪一天会是你的lucky day\n");
printf("开始喽,你有三次机会,开始猜吧(1~31):");
srand(time(0));
z=rand()%32;
scanf("%d",&x);
while(y<3){
if(x==z)
{
printf("\n猜中啦!你的lucky day是%d号",z);
break;
}
else if(x<z)
{
printf("\n你猜的日期早了,lucky day还在后面呢\n");
y++;
}
else if(x>z)
{
printf("\n你猜的日期晚了,lucky day悄悄溜到前面啦\n");
y++;
}
printf("\n再猜(1~31):");
scanf("%d",&x);
}
if(y=3){
printf("\n次数用完啦,偷偷告诉你,12月,你的lucky day是%d号\n",z);
}
return 0;
}