c++ - C++中使用getline函数提取某些字符

Question

我只需要从文本文件中获取特定字符。我在 C++ 中使用 getline() 函数。我的编译器一直给我错误，没有匹配的成员函数调用 getline()，我该如何解决？我正在尝试从文件中提取姓氏和分数。

文件看起来像:

Weems 50 60

Dale 51 60

Richards 57 60
...

这是我正在尝试的代码:

#include <iostream>
#include <cmath>
#include <fstream>

using namespace std;

int main ()
{
    //input variables
    float GradeScore;
    float TotalPoints;
    float GradePercent;
    string LastName;

    ifstream myFile;

    //open file
    myFile.open ("/Users/ravenlawrence/Documents/TestGrades.rtf",ios::in);
    // if file is open
    if (myFile.is_open()) {
        while(!myFile.eof()) {
            string data;
            getline(myFile,data); //reading data on line
            myFile.getline(LastName, ' ');//storing data in LastName 
            myFile.getLine(GradeScore,' ');//storing data in GradeScore 
            myFile.getLine(TotalPoints,' ');//storing data in Total Points 
            cout << LastName << endl;
            // cout<<data<<endl; //print it out
        }
    }
    return 0;
}

Answer 1

从设计开始，将工作分解成小步骤:

open file
loop, reading line from file while more lines
    split line into fields
    convert fields into variables
    display variables

现在处理每一步

// open file
ifstream myFile ("/Users/ravenlawrence/Documents/TestGrades.rtf",ios::in);
if( ! myFile ) {
  cerr << "cannot open file\n";
  exit(1);
}

//loop, reading line from file while more lines
string data;
while( getline( myFile, data ) ) {

   // split line into fields
   std::stringstream sst(data);
   std::string a;
   std::vector<string> vfield;
   while( getline( sst, a, ' ' ) )
       vfield.push_back(a);

   // ignore lines that do not contain exactly three fields
   if( vfield.size() != 3 )
      continue;

   //convert fields into variables
   LastName = vfield[0];
   GradeScore = atof( vfield[1].c_str() );
   TotalPoints = atof( vfield[2].c_str() );

   // display
   ...
}