#include<stdio.h>#include<math.h>#include<conio.h>float areatri(float a,float b,float    c);float main(){    float a,b,c;    float s;    char d;loop:    printf("输入三角形三边长，以空格隔开\n");    scanf("%f %f %f",&a,&b,&c);    s=areatri(a,b,c);    if(s<=0)        printf("error~\n");    else        printf("area=%f\n",s);    printf("按1开始新计算，按2退出\n");    scanf("%c",&c);    d=getch();    if(d==‘1‘)        goto loop;    if(d==‘2‘)        ;}float areatri(float a,float b,float    c){    float s,p;    if(a>0&&b>0&&c>0)    {        p=0.5*(a+b+c);        s=sqrt(p*(p-a)*(p-b)*(p-c));        return s;    }}