[read csv by cpp] c++读取csv文件 #c++ #csv

csv.cpp

#include "csv.h"

inline
std::vector<std::string> split_csv_line(const std::string& str) {
    char seperator = ',';
    std::vector<std::string> results;

    std::string::size_type start = str.find_first_not_of(' ');
    std::string::size_type sep = str.find(seperator);
    while (sep != std::string::npos) {
        if (start < sep)
            results.emplace_back(trim(str.substr(start, sep - start)));

        start = sep + 1;
        sep = str.find(seperator, start);
    }

    if (start != str.size())
        results.emplace_back(trim(str.substr(start)));

    return results;
}


std::vector<std::string> CsvReader::read_first_line(){
    if(!ifs_.is_open()){
        return {};
    }
    auto pos = ifs_.tellg();
    DEFER{ ifs_.seekg(pos,std::ios::beg); };
    std::string line_str;
    std::getline(ifs_, line_str);
    if(line_str.empty()){
        return {};
    }
    return split_csv_line(line_str);

}
std::vector<std::string>  CsvReader::read_line(){
    if(!ifs_.is_open()){
        return {};
    }
    std::string line_str;
    std::getline(ifs_, line_str);
    if(line_str.empty()){
        return {};
    }
    return split_csv_line(line_str);
}

std::vector<std::vector<std::string> > CsvReader::read_all(){
    std::vector<std::vector<std::string> > res;
    std::vector<std::string> line;
    do{
        line = read_line();
        if(!line.empty()){
            res.emplace_back(line);
        }
    }while(!line.empty());
    return res;
}

csv.h

#include <tuple>
#include <vector>
#include <string>
#include <fstream>

class CsvReader{
public:
    CsvReader(std::string csv_file){ifs_.open(csv_file);};
    ~CsvReader(){ ifs_.close();};
    bool is_open(){return ifs_.is_open();};

    std::vector<std::string> read_line();
    std::vector<std::string> read_first_line();
    std::vector<std::vector<std::string>> read_all();
private:
    std::ifstream ifs_;
};