利用海伦公式求三角形面积，因此先利用两点距离公式求得边长，即可求出面积

一、实现代码

#include <iostream> #include <cmath> using namespace std; int transform(char* str, int* coord); //提取数字函数 double length(int* a, int* b); //计算边长函数 int main() { char str[10]; //输入的字符串 int coord1[2], coord2[2], coord3[2]; //储存三个坐标值 int judge; for (int i = 0; i < 3; i++) {   cout << "坐标" << i << "："; gets_s(str); switch (i + 1) { case 1:    judge = transform(str, coord1); break; case 2:    judge = transform(str, coord2); break; case 3:    judge = transform(str, coord3); break; } if (judge != 2) //输入的坐标不是两个数字 {    cout << "坐标中必须只有两个数字组成！" << endl;    i--; //重新输入 } }  cout << "三个坐标分别为：（" << coord1[0] << "," << coord1[1] << ")，（" << coord2[0] << "," << coord2[1] << "），（" << coord3[0] << "," << coord3[1] << "）" << endl;; double p, a, b, c; //半周长，三边长度 double s; //面积   a = length(coord1, coord2);  b = length(coord3, coord2);  c = length(coord1, coord3);  p = (a + b + c) / 2;   cout << "三边长度：" << a << "，" << b << "，" << c << endl;   s = sqrt(p * (p - a) * (p - b) * (p - c)); //海伦公式   cout << "面积：" << s << endl;; return 0; } int transform(char* str, int* coord) //提取数字 { int count = 0; //0-x;1-y for (int i = 0; i < 10; i++) { while (str[i] && (str[i] < '0' || str[i] > '9')) //跳过非数字部分    i++; if (str[i]) {    coord[count] = str[i] - '0'; //字符转换 if (str[i + 1] >= '0' && str[i + 1] <= '9') //判断后一位 {     coord[count] = coord[count] * 10 + str[i + 1] - '0'; //数字累和     i++; //往后挪1 }    count++; } else //字符为空 break; } return count; } double length(int* a, int* b) //计算边长 { int subx, suby; double len;   subx = abs(a[0] - b[0]); //x坐标之差的绝对值  suby = abs(a[1] - b[1]); //y坐标之差的绝对值   len = sqrt(pow(subx, 2) + pow(suby, 2)); //两点距离公式，得边长 return len; } 

二、运行效果

如有不足之处，还望指正 ¹。