C++ 读写文本文件

1. 逐行读文本，文本以空格分隔

points.txt 文件内容如下：

index x1 y1 x2 y2

0 247 372 264 614

1 224 158 246 400

2 389 264 407 509

3 466 43 490 289

4 33 379 49 618

5 237 63 260 305

6 288 151 309 395

string filename="./points.txt";
fstream file;
vector<Point2f>vp1,vp2;
file.open(filename,ios_base::in);
string line;
while (!file.eof())
{
    getline(file,line);
    int index;
    float x1,y1,x2,y2;
    stringstream data(line);
    data>>index>>x1>>y1>>x2>>y2;
    vp1.push_back(Point2f(x1,y1));
    vp2.push_back(Point2f(x2,y2));
}
file.close()

2. 逐行读文本，文本以","分隔

points.txt文件内容如下

 index x1 y1 x2 y2

0,247,372,264,614

1,224,158,246,400

2,389,264,407,509

3,466,43,490,289

4,333,379,49,618

5,237,63,260,305

6,288,151,309,395

string filename = "./points.txt";
ifstream file(filename);
getline(file, line);
vector<string> vecIndex;
vector<double> vecx1,vecy1,vecx2,vecy2;
while (!file.eof())
{
    string line;
    if (getline(file, line)) {
        stringstream ss(line);
        string name;
        double x1, yl, x2, y2;
        string tmp;
        int i = 0;
        while (getline(ss, tmp, ',')) {
            if (i == 0) { name = tmp; vecIndex.push_back(name); }
            if (i == 1) { x1 = stod(tmp); vecx1.push_back(x1); }
            if (i == 2) { yl = stod(tmp); vecy1.push_back(y1); }
            if (i == 3) { x2 = stod(tmp); vecx2.push_back(x2); }
            if (i == 4) { y2 = stod(tmp); vecy2.push_back(y2); }
            i++;
        }
    }
}
file.close();