c++跳过csv文件的第一行

Question

我让我的程序从 .csv 文件中读取数据并输出数据，但我不希望它输出第一行。我试过使用 getline(data, line);和 stream.ignore ( std::numeric_limits<std::streamsize>::max(), '\n' ); .虽然它确实跳过了第一行，但最后两行打印了两次并混淆了。

string ID;
string sentenceIn;
string servedIn;
int sentence;
int served;
string lastName;
string firstName;

vector<string> idNum;
vector<string> sentenceLen;
vector<string> servedTime;
vector<string> lastNameIn;
vector<string> firstNameIn;


ifstream data("prisoner_data.csv");

if (data.is_open())
{
    cout << "File opened successfully." << endl << endl;
    while (data.good()) // !someStream.eof()
    {
        getline(data, ID, ',');
        cout << ID << "  ";
        idNum.push_back(ID);

        getline(data, sentenceIn, ',');
        cout << sentenceIn << "  ";
        sentenceLen.push_back(sentenceIn);
        istringstream(sentenceIn) >> sentence;

        getline(data, servedIn, ',');
        cout << servedIn << "  ";
        servedTime.push_back(servedIn);
        istringstream(servedIn) >> served;

        getline(data, lastName, ',');
        lastNameIn.push_back(lastName);
        cout << lastName << "  ";

        getline(data, firstName, ',');
        firstNameIn.push_back(firstName);
        cout << firstName << "  ";
    }
}

我该怎么做才能跳过第一行而不弄乱最后一行？

Answer 1

while (data.good())有腥味。你最终“吃掉”了一行。参见例如Why is iostream::eof inside a loop condition considered wrong?更多细节。您通常必须测试 getline 的结果直接在 while , 喜欢

while(getline(data, line)){...}

一种可能的解决方案是使用 while(getline(data, line)){...} 逐行读取文件然后使用 stringstream(line)对于每一行，用 getline 解析它再次，现在由 , 分隔.要跳过第一行，只需执行 getline(data, line);之前，然后跟进 while(getdata(data, line)){ /* process line */} .下面是一个简单的例子:

#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
#include <cstdlib>

int main()
{     
    std::ifstream data("prisoner_data.csv");
    if (!data.is_open())
    {
        std::exit(EXIT_FAILURE);
    }
    std::string str;
    std::getline(data, str); // skip the first line
    while (std::getline(data, str))
    {
        std::istringstream iss(str);
        std::string token;
        while (std::getline(iss, token, ','))
        {   
            // process each token
            std::cout << token << " ";
        }
        std::cout << std::endl;
    }
}