how to manipulate the txt file using C++ STL HOmework - c++

Question

I have a txt file that contains name, id number, mobilenumber, and location in comma separated line.
example
Robby, 7890,7788992356, 123 westminister
tom, 8820, 77882345, 124 kingston road
My task is to retrieve
Look up all of an employee's information by name.
Look up all of an employee's information by ID.
Add the information of an employee.
Update the information of an employee.
SO far I have read the file and stored the information in a vector. Code is shown below.
For tasks
1)Look up all of an employee's information by name. I will iterate in the vector and prints information containing the name . I will be able to do that
2) simialry in text file I will look for id and prints information about that.
BUT I am clueless about point 3 & 4.
I am posting my code below
void filter_text( vector<string> *words, string name)
{
vector<string>::iterator startIt = words->begin();
vector<string>::iterator endIt = words->end();
if( !name.size() )
std::cout << " no word to found for empty string ";
while( startIt != endIt)
{
string::size_type pos = 0;
while( (pos = (*startIt).find_first_of(name, pos) ) != string::npos)
std:cout <<" the name is " << *startIt<< end;
startIt++;
}
}
int main()
{
// to read a text file
std::string file_name;
std::cout << " please enter the file name to parse" ;
std::cin >> file_name;
//open text file for input
ifstream infile(file_name.c_str(), ios::in) ;
if(! infile)
{
std::cerr <<" failed to open file\n";
exit(-1);
}
vector<string> *lines_of_text = new vector<string>;
string textline;
while(getline(infile, textline, '\n'))
{
std::cout <<" line text:" << textline <<std::endl;
lines_of_text->push_back(textline);
}
filter_text( lines_of_text, "tony");
return 0;
}

Answer 1

#include <string>
#include <iostream>
#include <vector>
#include <stdexcept>
#include <fstream>
struct bird {
std::string name;
int weight;
int height;
};
bird& find_bird_by_name(std::vector<bird>& birds, const std::string& name) {
for(unsigned int i=0; i<birds.size(); ++i) {
if (birds[i].name == name)
return birds[i];
}
throw std::runtime_error("BIRD NOT FOUND");
}
bird& find_bird_by_weight(std::vector<bird>& birds, int weight) {
for(unsigned int i=0; i<birds.size(); ++i) {
if (birds[i].weight< weight)
return birds[i];
}
throw std::runtime_error("BIRD NOT FOUND");
}
int main() {
std::ifstream infile("birds.txt");
char comma;
bird newbird;
std::vector<bird> birds;
//load in all the birds
while (infile >> newbird.name >> comma >> newbird.weight >> comma >> newbird.height)
birds.push_back(newbird);
//find bird by name
bird& namebird = find_bird_by_name(birds, "Crow");
std::cout << "found " << namebird.name << '\n';
//find bird by weight
bird& weightbird = find_bird_by_weight(birds, 10);
std::cout << "found " << weightbird.name << '\n';
//add a bird
std::cout << "Bird name: ";
std::cin >> newbird.name;
std::cout << "Bird weight: ";
std::cin >> newbird.weight;
std::cout << "Bird height: ";
std::cin >> newbird.height;
birds.push_back(newbird);
//update a bird
bird& editbird = find_bird_by_name(birds, "Raven");
editbird.weight = 1000000;
return 0;
}
Obviously not employees, because that would make your homework too easy.

Answer 2

So, first off, I don't think you should store the information in a vector of strings. This kind of task totally calls for the use of a
struct employee {
int id;
std::string name;
std::string address;
//... more info
};
And storing instances of employees in an
std::vector<employee>
You see, using your strategy of storing the lines, searching for "westminster" would net me Robbie, as his line of text does include this substring, but his name isn't westminster at all. Storing the data in a vector of employee structs would eliminate this problem, and it'd make the whole thing a lot more, well, structured.
Of course you'd need to actually parse the file to get the info into the vector. I'd suggest using a strategy like:
while(getline(infile, textline, '\n')) {
std::stringstream l(textline);
getline(l,oneEmp.name, ','); //extract his name using getline
l >> oneEmp.id; //extract his id
//extract other fields from the stringstream as neccessary
employees.push_back(oneEmp);
}
As for adding information: when the user enters the data, just store it in your employees vector; and when you should need to update the file, you may simply overwrite the original data file with a new one by opening it for writing & dumping the data there (this is obviously a rather wasteful strategy, but it's fine for a school assignment (I suppose it's school assignment)).

Answer 3

Start by splitting the CSV line into separate fields and then populate a struct with this data
eg:
struct Employee
{
std::string name;
std::string id_number;
std::string mobilenumber;
std::string location;
};
std::vector<Employee> employees; // Note you dont need a pointer
Look at string methods find_first_of, substr and friends.