C语言海伦公式计算三角形面积

╰半橙微兮° 2022-03-15 17:50 288阅读 0赞

**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：
    3
    1 2 3
    3 4 5
    5 12 13
    输出示例：
    0.00
    6.00
    30.00
    Author: Zhang Kaizhou
    Date: 2019-3-7 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;
    }