Reading information into array of structs c++ - c++

Question

I'm making a program for my c++ class. Ultimately I want my program to perform a quicksort on a text file of contacts in the following format:
Firstname Secondname Number
Each contact is separated by a new line. I've started by counting the number of lines and using dynamic memory allocation to create an array of structs which has the same size as the number of lines.
However, when I tried to read in the information from the text file and output it to the screen, all I get is gibberish. I've had a look around on the internet to try and find a solution but everything I've found seems to use a different syntax to me.
Here's my code so far:
#include <iostream>
#include <fstream>
#include <istream>
char in[20];
char out[20];
using namespace std;
struct contact
{
char firstName[14];
char surName[14];
char number[9];
};
//structure definition
int main(void){
cout << "Please enter the input filename: " << endl;
cin >> in;
ifstream input(in);
if(!input){
cerr << "failed to open input file " << in << endl;
exit(1);
}
cout << "Please enter tne output filename: " << endl;
cin >> out;
// read in the input and output filenames
char a;
int b=0;
while (input.good ())
{
a=input.get ();
if (a=='\n')
{
b++;
}
}
// count the number of lines in the input file
input.seekg (0, ios::beg);
//rewind to beginning of file
contact* list = new contact[b];
//dynamically create memory space for array of contacts
int i = 0.;
while(input){
if(i >= b) break;
if(input >> *list[i].firstName >> *list[i].surName >> *list[i].number) i++;
else break;
}
input.close();
//read information from input file into array of contacts
for(int N = 0; N < b; N++){
cout << list[N].firstName << list[N].surName << list[N].number << endl;
}
ofstream output(out);
int k = 0;
for(int k = 0; k<b; k++){
output << list[k].firstName << " " << list[k].surName << " " << list[k].number << endl;
}
//print out the unsorted list to screen and write to output file
//i've done both here just to check, won't print to screen in final version
output.close();
delete []list;
} // end of main()

Answer 1

You reset the files location to the beginning, but the files eofbit is still labeled as true from when you first read the amount of lines. A quick fix to this is re-opening the file after you read the lines, possibly making the line count a function to clean up code.
int lines(const string path)
{
ifstream tmp(path.c_str());
string temp;
int count = 0;
getline(inFile,temp);
while(inFile)
{
count++;
getline(inFile,temp);
}
tmp.close();
return count;
}

Answer 2

Okay, I put together a quick and dirty method using newer C++ constructs to get you most of the way there. You're on your own for writing to the file (trivial) and the quicksort, though I've put the struct into a vector for you, so sorting the vector is as easy as writing a custom function to compare one struct vs the other. I apologize in advance if some of the code is less than canonical C++. I'm way past my bed time, and way tired, but this was interesting enough of a problem that I wanted to give it a go. Happy coding!
#include <iostream>
#include <fstream>
#include <istream>
#include <string>
#include <vector>
#include <algorithm>
#include <cctype>
#include <sstream>
using namespace std;
std::vector<std::string> &split(const std::string &s, char delim, std::vector<std::string> &elems) {
std::stringstream ss(s);
std::string item;
while(std::getline(ss, item, delim)) {
elems.push_back(item);
}
return elems;
}
std::vector<std::string> split(const std::string &s, char delim) {
std::vector<std::string> elems;
return split(s, delim, elems);
}
struct contact
{
std::string firstName;
std::string surName;
std::string number;
contact(std::string& fName, std::string& lName, std::string& num) : firstName(fName), surName(lName), number(num) {}
};
//structure definition
char in[20];
char out[20];
int main()
{
std::vector<contact> contacts;
cout << "Please enter the input filename: " << endl;
cin >> in;
ifstream input(in);
if(!input){
cerr << "failed to open input file " << in << endl;
exit(1);
}
cout << "Please enter tne output filename: " << endl;
cin >> out;
std::string sinput;
// read in the input and output filenames
while (input.good ())
{
getline(input, sinput);
vector<string> tokens = split(sinput, ' ');
if (tokens.size() == 3)
{
contact c(tokens[0], tokens[1], tokens[2]);
contacts.push_back(c);
}
}
input.close();
//read information from input file into array of contacts
std::cout << "Outputting from vector..." << std::endl;
for_each(contacts.begin(), contacts.end(), [](contact& c) {
cout << c.firstName << " " << c.surName << " " << c.number << endl;
});
return 0;
}
Also, just want to give credit that the split methods come from this answer on this very site. Cheers!