[C 结构体 文件] 读取直线、矩形、圆混合文件，并查询指定类型

【需要读取的文件】

LINE
0 0 10 10
RECT
10 10 20 20
CIRCLE
20 20 40
RECT
20 20 40 40
LINE
12 34 56 78
LINE
56 78 100 200
CIRCLE
11 22 33
END

【结果】

【完整答案】

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

typedef struct{
	char type[10];
	union{
		struct Line{
			double x0;
			double y0;
			double x1;
			double y1;
		}line;
		struct Rect{
			double x;
			double y;
			double width;
			double height;
		}rect;
		struct Circle{
			double x;
			double y;
			double r;
		}circle;
	}attr;
}Geometry;
typedef struct node{
	Geometry data;
	struct node *next;
}LNode, * LinkList;

LinkList ReadFile(char str[]); //读入文件
	LNode* ReadNext(FILE **fpp); //读入下一个Geometry
void PrintAllType(LinkList L, char type[]); //输出type的所有Geomtry
	void PrintGeometry(Geometry data); //输出Geometry
LNode* FreeAll(LNode *p); //释放所有空间


int main() {
	LinkList p;
	char type[10];

	p = ReadFile("2014-10.txt");

	printf(">>> 请输入要查询要素的类型："); //
	scanf("%s", type);
	PrintAllType(p, type);
	
	printf("\n正在删除.....\n");
	p = FreeAll(p);
	if (p==NULL) printf("\n删除成功\n");

	return 0;
}

LinkList ReadFile(char str[]) {
	LNode *p;
	FILE *fp;
	
	fp = fopen(str, "r"); 
	if (!fp) exit(0);
	p = ReadNext(&fp);
	fclose(fp);

	printf("读入完毕\n");

	return p;
}
LNode* ReadNext(FILE **fpp) {
	LNode *p;

	p = (LNode *)malloc(sizeof(LNode)); if (!p) exit(0);
	// 读类型
	fscanf(*fpp, "%s", p->data.type);
	if ( strcmp(p->data.type, "END")==0 ) { //退出
		printf("END\n");
		free(p);
		return NULL;
	}
	//读数值
	if (strcmp(p->data.type, "LINE")==0 ) {
		printf("LINE\n");
		fscanf(*fpp, "%lf%lf%lf%lf", &p->data.attr.line.x0, &p->data.attr.line.x1, &p->data.attr.line.y0, &p->data.attr.line.y1);
	} else if ( strcmp(p->data.type, "RECT")==0 ) {
		printf("RECT\n");
		fscanf(*fpp, "%lf%lf%lf%lf", &p->data.attr.rect.x, &p->data.attr.rect.y, &p->data.attr.rect.width, &p->data.attr.rect.height);
	} else if ( strcmp(p->data.type, "CIRCLE")==0 ) {
		printf("CIRCLE\n");
		fscanf(*fpp, "%lf%lf%lf", &p->data.attr.circle.x, &p->data.attr.circle.y, &p->data.attr.circle.r);
	}
	p->next = ReadNext(fpp);
	return p;
}
LNode* FreeAll(LNode *p) {
	LNode *next;
	if (!p) return NULL;

	next = p->next;
	printf("删除%s\n", p->data.type);
	free(p);
	return FreeAll(next);
}
void PrintAllType(LinkList L, char str[]) {
	if (!L) return ; //结束

	if ( strcmp(L->data.type, str)==0 ) {
		PrintGeometry(L->data);
	}

	PrintAllType(L->next, str);
}
void PrintGeometry(Geometry data) {
	printf("%s：", data.type);
	if ( strcmp(data.type, "LINE")==0 ) {
		printf("%lf %lf %lf %lf\n", data.attr.line.x0, data.attr.line.x1, data.attr.line.y0, data.attr.line.y1);
	} else if ( strcmp(data.type, "RECT")==0 ) {
		printf("%lf %lf %lf %lf\n", data.attr.rect.x, data.attr.rect.y, data.attr.rect.width, data.attr.rect.height);
	} else if ( strcmp(data.type, "CIRCLE")==0 ) {
		printf("%lf %lf %lf\n", data.attr.circle.x, data.attr.circle.y, data.attr.circle.r);
	}
}