C++简单的文件读写操作 -----（笔记）

C++简单的文件读写操作 -----（笔记）

#include<iostream>
#include<fstream>
#include<string>
#include<vector>
#include<cmath>
#include<climits>
#include <iomanip>
using namespace std;

class Point{
	private:
		char name;
		double x;
		double y;
	public:
		Point(char t_name,double t_x,double t_y)
			:name(t_name),y(t_y),x(t_x){}
		char getName(){
			return name;
		}
		double getX(){
			return x;
		}
		double getY(){
			return y;
		}
}; 

int main(){
	ifstream infile;
	infile.open("point.txt");
	double cmin = INT_MAX;
	vector<Point> vector;
	while(!infile.eof()){
		char name;
		double x;
		double y;
        //文件内每行格式为 A 1.5 2.5
		infile >> name >> x >> y;
		Point p(name,x,y);
		vector.push_back(p);
	}
	infile.close();
	ofstream outfile;
	outfile.open("out.txt");
	for(int i=0;i<vector.size();i++){
		for(int j=i+1;j<vector.size();j++){
			if(outfile.is_open()){
				double width = sqrt(pow(vector[i].getX()-vector[j].getX(),2)+pow(vector[i].getY()-vector[j].getY(),2));
				cmin = min(cmin,width);
				outfile << vector[i].getName() << "->" << vector[j].getName() << ": " << width << "\n";
			}
		}
	}
	outfile << "最短距离为：" << cmin << "\n";
	outfile.close();
}

测试样例 point.txt

A 2.4 3.5
B 5.4 1.6
C 5.7 8.3
D 6.3 5.2

输出文件 out.txt

A->B: 3.55106
A->C: 5.82495
A->D: 4.25441
B->C: 6.70671
B->D: 3.7108
C->D: 3.15753
最短距离为：3.15753