Reading formatted data from file in C++

Question

I am trying to write a code to read data from file. The file looks like:

47012   "3101 E 7TH STREET, Parkersburg, WV 26101"
48964   "S16 W22650 W. LINCOLN AVE, Waukesha, WI 53186"
.
.
.
.

I need to store the number as an int and the address as a string.

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main()
{
ifstream myfile;
myfile.open("input.txt");
long int id;
string address;
myfile >> id;
cout << id << endl;
myfile >> address;
cout << address.c_str() << endl;
myfile.close();
system("pause");
return 0;
}

The output of program

47012
"3101

The output that I need is

47012
3101 R 7TH STREET, Parkersburg, WV 26101

How do I go about doing this. Thanks in advance Any help is appreciated

Answer 1

I'd do something like the following. Nah, just kidding, I'd use Boost Spirit in real life. However, this seems like something you could attempt with standard library approaches too:

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

using namespace std;

int main()
{
    ifstream myfile("input.txt");

    std::string line;
    while (std::getline(myfile, line))
    {
        std::istringstream linereader(line, std::ios::binary);

        long int id;

        linereader >> id;
        if (!linereader)
            throw "Expected number";

        linereader.ignore(line.size(), '"');

        string address;
        if (!std::getline(linereader, address, '"'))
            throw "Expected closing quotes";

        cout << id << endl << address << endl;
    }
    myfile.close();
}

Printing:

47012
3101 E 7TH STREET, Parkersburg, WV 26101
48964
S16 W22650 W. LINCOLN AVE, Waukesha, WI 53186

Answer 2

Simply use getline :

while (in >> id) {
    if (!getline(in, address)) {
        // (error)
        break;
    }

    // substr from inside the quotes
    addresses[id] = address.substr(1, address.length() - 2);
}

Answer 3

This doesn't work because the stream operator >> will take spaces as delimiter when trying to read strings.

You could use getline(stream, address, '\\t'); to read a string with a specific delimiter.

Or simply getline(stream, address) if there is nothing else to read on that line :

long int id;
string address;
myfile >> id;
getline(stream, address);

This is just an example, see @not-sehe 's answer for a complete solution (read the lines using getline and then parse each line using a stringstream ).

Answer 4

You can use cin.getline() which will read the remainder of the line.

First read the digit, then use getline() to read everything remaining.

Answer 5

The >> operator terminates a string at a space.I would recommend using

char temp[100];
myfile.getline(temp,max_length);

This reads a line at a time.Then you can use a loop to split the line in the way you want.

I would like to add that you might need the atoi(char *) (from module cytpe.h ) function to convert an integer string to an integer.

Answer 6

    getline(myfile, address, '"');//dummy read skip first '"'
    getline(myfile, address, '"');