#include <stdio.h>
int main(){
    double x1,y1,x2,y2,x3,y3,s;
    while(1){
        scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
        if(x1==0&&x2==0&&x3==0&&y1==0&&y2==0&&y3==0)break;
        s=0.5*(x1*(y2-y3)+x2*(y3-y1)+x3*(y1-y2));
        if(s<0)s=-s;
        printf("%.1f\n",s);
    }
}

#include<stdio.h>
#include<iostream>
#include <iomanip>
using namespace std;
const int N=100010;
int f[N];
int g[N];
double S;
int main()
{
	while(1)
{
		for(int i=1;i<=3;i++)
	{
		cin>>f[2*i-1]>>g[2*i];
	}	
	if(f[5]==0&&f[3]==0&&f[1]==0&&g[2]==0&&g[4]==0&&g[6]==0)
	{
		break;
	}
	S=0.5*(f[1]*(g[4]-g[6])+f[3]*(g[6]-g[2])+f[5]*(g[2]-g[4]));	
	if(S<0)
	{
		S=S*-1;
	}
    cout << fixed << setprecision(1) << S << endl;
}
	
	return 0;
}
最近迷上了数组

#include<stdio.h> #include<math.h>

int main() { int a,b,c,d,e,f; while(scanf("%d %d %d %d %d %d",&a,&b,&c,&d,&e,&f)!=EOF) { if(a0&&b0&&c0&&d0&&e0&&f0) break; double s; s=(ad+cf+eb-af-cb-ed)*0.5; if(s<0) s=-s; printf("%.1lf\n",s); } }

#include<stdio.h> #include<math.h> int main() { int x1,y1,x2,y2,x3,y3; double s; scanf("%d %d %d %d %d %d",&x1,&y1,&x2,&y2,&x3,&y3); while(x1!=0||y1!=0||x2!=0||y2!=0||x3!=0||y3!=0) { s=0.5abs((x1-x3)(y2-y3)-(x2-x3)*(y1-y3));

printf("%.1lf\n",s); scanf("%d %d %d %d %d %d",&x1,&y1,&x2,&y2,&x3,&y3); } return 0; }

#include<stdio.h>
#include<math.h>
int main()
{
 int x1, y1, x2, y2, x3, y3;
 double p, p1, p2, p3, s;
 scanf("%d %d %d %d %d %d", &x1, &y1, &x2, &y2, &x3, &y3);
 while (x1!= 0||y1!= 0||x2!= 0||y2!= 0||x3!= 0||y3!= 0)
 {
 p1 = sqrt(pow(y2 - y1, 2) + pow(x2 - x1, 2));
 p2 = sqrt(pow(y3 - y2, 2) + pow(x3 - x2, 2));
 p3 = sqrt(pow(y1 - y3, 2) + pow(x1 - x3, 2));
 p = (p1 + p2 + p3) /2;
 s = sqrt(p*(p - p1)*(p - p2)*(p - p3));
 printf("%.1f\n", s);
 scanf("%d %d %d %d %d %d", &x1, &y1, &x2, &y2, &x3, &y3);
 }
 return 0;

}
//float貌似过不去