为什么会报错?求解答

#include<stdio.h>
#include<math.h>
double area(double x,double y,double z);
{
double p=(x+y+z)/2;
return sqrt(p*(p-x)(p-y)(p-z));
}
int main()
{
double a1,a2,a3,a4,a5,a6,a7,s;
printf("input 7 sise lengths in the order a1 to a7:\n");
scanf("%lf%lf%lf%lf%lf%lf%lf",&a1,&a2,&a3,&a4,&a5&,a6,&a7);
s=area(a1,a5,a6)+area(a4,a6,a7)+area(a2,a3,a7);
printf("the area of the pentagon is:%.2f\n",s);
return 0;
}

double area(double x,double y,double z);
后面的分号删除掉
另外函数里你应该检查一下三条边长度是否能够组成三角形，否则sqrt的参数可能是个负数，会出问题的

#include<stdio.h>
#include<math.h>
double area(double x,double y,double z)
{
double p=(x+y+z)/2;
if(x+y>z || y+z>x || x+z>y)
    return 0;
return sqrt(p*(p-x)*(p-y)*(p-z));
}
int main()
{
double a1,a2,a3,a4,a5,a6,a7,s;
printf("input 7 sise lengths in the order a1 to a7:\n");
scanf("%lf%lf%lf%lf%lf%lf%lf",&a1,&a2,&a3,&a4,&a5,&a6,&a7);
s=area(a1,a5,a6)+area(a4,a6,a7)+area(a2,a3,a7);
printf("the area of the pentagon is:%.2f\n",s);
return 0;
}

double area(double x,double y,double z) //之后多了;
scanf("%lf%lf%lf%lf%lf%lf%lf",&a1,&a2,&a3,&a4,&a5&,a6,&a7);
a6前面的, 和&写反了
你题目的解答代码如下：

#include<stdio.h>
#include<math.h>
double area(double x,double y,double z) //之后多了;
{
    double p=(x+y+z)/2;
    return sqrt(p*(p-x)*(p-y)*(p-z));
}
int main()
{
    double a1,a2,a3,a4,a5,a6,a7,s;
    printf("input 7 sise lengths in the order a1 to a7:\n");
    scanf("%lf%lf%lf%lf%lf%lf%lf",&a1,&a2,&a3,&a4,&a5,&a6,&a7);//a6前面的, 和&写反了
    s=area(a1,a5,a6)+area(a4,a6,a7)+area(a2,a3,a7);
    printf("the area of the pentagon is:%.2f\n",s);
    return 0;
}

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