C++读写txt文件

参考https://blog.youkuaiyun.com/u010220351/article/details/52347631

1、读txt

目标txt文件：

代码：

#include <fstream>    

int main()
{
    ifstream infile;
    infile.open("edge.txt");
    int v1,v2;
    while(infile>>v1>>v2)
    {
        cout<<v1<<" "<<v2<<endl;	
    }
    infile.close();
}

结果：

2、读进来，写出去

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
using namespace std;

int main()
{
	ifstream infile;
    infile.open("Gowalla_totalCheckins.txt");
    int userID;
    string time;
    double longitude,latitude; 
    int tem;
    
    ofstream outfile;
    outfile.open("points.txt");
    int preID=-1;
    int cnt=0;
    while(infile>>userID>>time>>longitude>>latitude>>tem)
    {
    	
        if(userID!=preID){//新的用户的第一个位置 
        	outfile<<userID<<" "<<longitude<<" "<<latitude<<endl;
        	preID=userID;
       	 	cnt++;
       	 	cout<<cnt<<endl;
    		//if(cnt==100) break;
		}
    }
    infile.close();
    outfile.close();
}