关键点：
1.注意scanf()函数的输入特点，回车符仍会留在输入缓冲区，故需注意及时清理输入缓冲区内容，避免造成输入逻辑的混乱；
2.注意三角形构成条件的判定。
/*--------------------------------------------------------------功能：利用海伦公式求三角形面积，若三边无法构成三角形，则面积为0输入示例：31 2 33 4 55 12 13输出示例：0.006.0030.00Author: Zhang KaizhouDate: -3-7 11:05:04---------------------------------------------------------------*/#include <stdio.h>#include <stdlib.h>#include <math.h>typedef struct node{float eadge[3];float area;struct node * pnext;} Node;void compute_area(Node * p);void list_tail_insert(Node ** pphead, Node ** pptail, Node * p);void list_print(Node * phead);int main(){Node * phead = NULL, * ptail = NULL;int n, i;scanf("%d", &n);getchar(); // 取出输入缓冲区的回车符for(i = 0; i < n; i++){Node * pnew = (Node *)calloc(1, sizeof(Node));scanf("%f %f %f", &pnew->eadge[0], &pnew->eadge[1], &pnew->eadge[2]);compute_area(pnew);list_tail_insert(&phead, &ptail, pnew);}list_print(phead);free(phead);free(ptail);return 0;}void compute_area(Node * p){float a, b, c;float q; //半周长a = p->eadge[0];b = p->eadge[1];c = p->eadge[2];if(a + b < c || a + c < b || b + c < a || abs(a - b) > c || abs(a - c) > b || abs(b - c) > a){p->area = 0;}else{q = (a + b + c) / 2;p->area = sqrt(q * (q - a) * (q - b) * (q - c));}return;}void list_tail_insert(Node ** pphead, Node ** pptail, Node * p){if(* pphead == NULL){* pphead = p;* pptail = p;}else{(* pptail)->pnext = p;* pptail = p;}return;}void list_print(Node * phead){while(phead != NULL){printf("%.2f\n", phead->area);phead = phead->pnext;}return;}
