在csv中的线读取非常奇怪 [英] Getline reading in a csv very oddly

问题描述

我想读取csv使用get行提取三个变量用逗号分隔。

我在第一行读得很好，但它放入了奇怪的换行符，并将格式发送到集群中。

这是我的代码：

  #includeheader.h
 
 string student :: GetCourse（）{
 return course; 
} 
 
 string student :: GetName（）{
 return name; 
} 
 
 string student :: GetGrade（）{
 return grade; 
} 
 
 void student :: setname（string n）{
 name = n; 
} 
 
 void student :: setCourse（string c）{
 course = c; 
} 
 
 void student :: setGrade（string g）{
 grade = g; 
} 
 void sort（vector< student>& List）{
 
 student temp; 
 int first = 1; 
 int vectorLength = List.size（） -  1; 
 
 for（int i = vectorLength; i> 0; i--）{
 first = i; 
 for（int j = 0; j  if（List [j] .GetName（）> List [first] .GetName（））
 first = j; 
} 
 temp = List [first] 
 List [first] = List [i]; 
 List [i] = temp; 
} 
 
} 
 
 void main（）{
 ifstream file; 
矢量< student>学生列表; 
 
 file.open（short.txt）; 
 
 while（！file.eof（））{
 
 file.ignore（8196，'\\\
'）; 
 
 string tempname，tempgrade，tempcourse =; 
 
 if（file！=\\\
）{
 getline（file，tempname，'，'） 
 getline（file，tempcourse，'，'）; 
 getline（file，tempgrade，'，'）; 
} 
 
 student s; 
 s.setCourse（tempcourse）; 
 s.setname（tempname）; 
 s.setGrade（tempgrade）; 
 
 StudentList.push_back（s）; 
 
} 
 // sort（StudentList）; 
 
 for（int i = 0; i  cout< StudentList [i] .GetName（）< < StudentList [i] .GetCourse（）< < StudentList [i] .GetGrade（）< endl; 
} 
} 
  

任何想法，我有一个真正的困难时期

b b $ b

如果（file！=\\\
）比较是无意义的。

成绩之后的分隔符不是'，'，它是'\\\
'。

while（！file.eof（））不正确。只有在EOF已经发生之后才检查。您应该检查 getline（）的返回值

/ p>

• 通常在C ++中，您可以 std :: ifstream file（short.txt）; 。您不需要分别调用 open（）。



• 您不需要初始化 std :: string 更改为。这会自动发生。即使你不得不这样做，你应该写成

  
  
  

  std :: string a =，b = ; 。

  
  
  

  如果你执行 std :: string a，b，c =something

I am trying to read a csv using get line to extract three variables separated by commas. Name, Course, and Grade.

I am reading in the first line fine but it puts in weird new line breaks and sends the format into a cluster.

Here is my code :

#include "header.h"

string student::GetCourse() {
    return course;
}

string student::GetName() {
    return name;
}

string student::GetGrade() {
    return grade;
}

void student::setname(string n) {
    name = n;
}

void student::setCourse(string c) {
    course = c;
}

void student::setGrade(string g) {
    grade = g;
}
void sort (vector <student> &List) {

    student temp;
    int	first = 1;
    int vectorLength = List.size() - 1;

    for (int i = vectorLength; i > 0; i--) {
    	first = i;
    	for (int j = 0; j < i; j++) {
    		if (List[j].GetName() > List[first].GetName())
    		first = j;
    	}
    	temp = List[first];
    	List[first] = List[i];
    	List[i] = temp;
    }

}

void main () {
    ifstream file;
    vector <student> StudentList;

    file.open("short.txt");

    while (!file.eof()) {

    	file.ignore(8196,'\n');

    	string tempname, tempgrade, tempcourse = "";

    	if (file != "\n") {
    		getline(file, tempname, ',');
    		getline(file, tempcourse, ',');
    		getline(file, tempgrade, ',');
    	}

    	student s;
    	s.setCourse(tempcourse);
    	s.setname (tempname);
    	s.setGrade (tempgrade);

    		StudentList.push_back(s);

    }
    //sort (StudentList);

    for (int i = 0; i < StudentList.size(); i++) {
    	cout << StudentList[i].GetName() << " " << StudentList[i].GetCourse() << " " << StudentList[i].GetGrade() << endl;
    }
}

Any ideas, I am having a real hard time on reading in this file.

解决方案

Well, here goes

• if (file != "\n") comparison is nonsensical. It does not do what you think it does.
• Your delimiter after the grade is not ',', it is '\n'.
• while (!file.eof()) is incorrect. That only checks the EOF after it has already happened. You should check the return value of your getline() instead

Also

• usually in C++ you do std::ifstream file("short.txt");. You don't need to call open() separately.

• You don't need to initialize std::string to "". That happens automatically. Even if you had to do that, then you should have written

  std::string a = "", b = "", c = "";.

  If you do std::string a, b, c = "something" then only c is initialized to something.

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