Affichage d'un fichier.txt en C++ (SOS)

#include <fstream>
#include <iostream>
#include <string>

int main(){
    const char *filename = "plop.txt";
    std::ifstream ifs(filename);
    if(!ifs){
        std::cerr << "Le fichier [" << filename 
           << "] n'existe pas" << std::endl;
        return 1;
    }
    std::string line;
    while(std::getline(ifs,line)) std::cout << line << std::endl;
    ifs.close();
    return 0;
}

(mando@cenedra) (~) $ g++ -W -Wall plop.cpp
(mando@cenedra) (~) $ cat plop.txt
1       2       3
4       5       6
7       8       9
10      11      12
(mando@cenedra) (~) $ ./a.out
1       2       3
4       5       6
7       8       9
10      11      12

#include <fstream>
#include <iostream>
#include <string>
#include <cstdio>
#include <vector>

// Une classe de matrice pleine
template <typename T>
class matrix_t : public std::vector<std::vector<T> >{
    public:
    inline unsigned get_nb_row() const{
        return this->size();
    }

    inline unsigned get_nb_col() const{
        return (this->size() == 0 ? 0 : (*this)[0].size());
    }
};

/**
 * \brief Lit un fichier tabulé de doubles (9 par ligne)
 * \param ifs Le fichier à lire
 * \return La matrice lue
 */
matrix_t<double> read_matrix_file(std::ifstream & ifs){
    matrix_t<double> matrix;
    std::string line;
    for(unsigned no_line=1;std::getline(ifs,line);++no_line){
        // Parser la ligne courante
        std::vector<double> row(9);
        if(sscanf(line.c_str()," %lf %lf %lf %lf %lf %lf %lf %lf %lf ",
            &row[0],&row[1],&row[2],&row[3],&row[4],
            &row[5],&row[6],&row[7],&row[8]
        ) == 9){
            matrix.push_back(row);
        }else{
            std::cerr << "ligne " << no_line << ": " << line << std::endl
                << "nombre de valeurs invalides, ligne ignorée" << std::endl;
            continue;
        }
    }
    return matrix;
}


int main(){
    // Lire le fichier
    matrix_t<double> matrix;
    {
        const char *filename = "plop.txt";
        std::ifstream ifs(filename);
        if(!ifs){
            std::cerr << "Le fichier [" << filename
                << "] n'existe pas" << std::endl;
            return 1;
        }
        matrix = read_matrix_file(ifs);
        ifs.close();
    }

    // Afficher la matrice
    {
        unsigned nb_col = matrix.get_nb_col();
        unsigned nb_row = matrix.get_nb_row();
        for(unsigned i=0;i<nb_row;++i){
            for(unsigned j=0;j<nb_col;++j){
                std::cout << matrix[i][j] << '\t';
            }
            std::cout << std::endl;
        }
    }

    return 0;
}

./plop.exe | more

./plop.exe > log.txt

plop.exe > log.txt