#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;
}
#include <stdio.h>
#include <math.h>
int main(){
int i;
int m,n;
int count;
count=0;
for(m=101;m<=200;m++){
n=sqrt(m);
for(i=2;i<=n;i++){
if(m%i==0)break;
}
if(i>n){
printf("%6d",m);
count++;
if (count%5==0)
printf("\n");
}
}
printf("\n101~200间有%d个素数.",count);
return 0;
}
#include <stdio.h>
#include <math.h>
int main(){
long int s;
int a=0,b=0,n=1;
printf("Enter a number:");
scanf("%ld",&s);
while(s>0){
a=s%10;
s=s/10;
if(a%2==1)
{b=b+a*n;
n=n*10;}
}
printf("Enter a new number:%d\n",b);
return 0;
}
#include <stdio.h>
#include <math.h>
int main(int argc, const char * argv[]) {
int n;
double s=0,num;
int x=0,a=1;
int i;
double sign=1.0;
loop:printf("Enter n(1~10):");
while(scanf("%d",&n)!=EOF){
for(i=1;i<=n;i++){
a=a*i;
do{
num=sign/a;
s=s+num;
sign=-sign;
x++;
continue;
}while(x<=n);
}
printf("n = %d,s = %f\n",n,s);
s=0;x=0;a=1;sign=1.0;
goto loop;
}
return 0;
}
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main(){
int n, x, i=1;
printf("猜猜2020年12月哪一天会是你的luck day\n");
printf("开始喽,你有三次机会,猜吧(1~31):");
srand(time(0));
x= rand()%32;
scanf("&d",&n);
while(i<3){
if(n == x){
printf("猜中啦!你的luck day是%d号",x);
break;
}
else if(n<x){
printf("你猜的日期早了,luck day还在后面呢\n");
i++;
}
else if(n>x){
printf("你猜的日期晚了,luck day悄悄溜到前面啦\n");
i++;
}
printf("再猜(1~31);");
scanf("%d",&n);
}
if(i=3){
printf("次数用完啦,偷偷告诉你,12月,你的luck day是%d号\n",x);
}
return 0;
}