C++ String Array, Loading lines of text from file

Question

I have a problem. When I try to load a file into a string array nothing shows.
Firstly I have a file that on one line has a username and on the second has a password.
I haven't finished the code but when I try to display what is in the array nothing displays.
I would love for this to work.

Any suggestions?

users.txt

user1
password
user2
password
user3
password

C++ Code

void loadusers()
{
string t;
string line;
int lineCount=0;
int lineCount2=0;
int lineCount3=0;

ifstream d_file("data/users.txt");
while(getline(d_file, t, '\n'))
++lineCount;

cout << "The number of lines in the file is " << lineCount << endl;

string users[lineCount];

while (lineCount2!=lineCount)
{
    getline(d_file,line);
    users[lineCount2] = line;
    lineCount2++;
}

while (lineCount3!=lineCount)
{
    cout << lineCount3 << "   " << users[lineCount3] << endl;
    lineCount3++;
}

d_file.close();
}

Answer 1

You cannot create arrays in C++ with runtime values, the size of the array needs to be known on compile time. To solve this you may use a vector for this ( std::vector )

You need the following include: #include <vector>

And the implementation for load_users would look like this:

void load_users() {
    std::ifstream d_file('data/users.txt');
    std::string line;
    std::vector<std::string> user_vec;

    while( std::getline( d_file, line ) ) {
        user_vec.push_back( line );
    }

    // To keep it simple we use the index operator interface:
    std::size_t line_count = user_vec.size();
    for( std::size_t i = 0; i < line_count; ++i ) {
        std::cout << i << "    " << user_vec[i] << std::endl;
    }
    // d_file closes automatically if the function is left
}

Answer 2

Use a std::vector<std::string>:

std::ifstream the_file("file.txt");
std::vector<std::string> lines;
std::string current_line;

while (std::getline(the_file, current_line))
    lines.push_back(current_line);

Answer 3

I guess you will find your best answer using istringstream.