How to put numbers from txt file into vector in c++ - c++

Question

I must say I'm completely new to C++. I got the following problem.
I've got a text file which only has one 8 digits number
Text-File: "01485052"
I want to read the file and put all numbers into a vector, e.g. Vector v = ( 0, 1, 4, 8, 5, 0, 5, 2 ). Then write it into another text file.
How do I implement it the best way? That's what I made possible so far:
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <sstream>
using namespace std;
int main()
{
char matrikelnummer[100];
cout << "Enter file name: ";
cin >> matrikelnummer;
// Declare input file stream variable
ifstream inputFile(matrikelnummer);
string numbers;
//Check if exists and then open the file
if (inputFile.good()) {
//
while (getline(inputFile, numbers))
{
cout << numbers;
}
// Close the file
inputFile.close();
}
else // In case TXT file does not exist
{
cout << "Error! This file does not exist.";
exit(0);
return 0;
}
// Writing solutions into TXT file called Matrikelnummer_solution.txt
ofstream myFile;
myFile.open("Matrikelnummer_solution.txt");
myFile << "Matrikelnummer: " << numbers << '\n';
myFile.close();
return 0;
}

Answer 1

You can use the following program for writing the number into another file and also into a vector:
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <sstream>
using namespace std;
int main()
{
ifstream inputFile("input.txt");
std::string numberString;
int individualNumber;
std::vector<int> vec;
if(inputFile)
{
std::ofstream outputFile("outputFile.txt");
while(std::getline(inputFile, numberString,'\n'))//go line by line
{
for(int i = 0; i < numberString.size(); ++i)//go character by character
{
individualNumber = numberString.at(i) - '0';
outputFile << individualNumber;//write individualNumber into the output file
vec.push_back(individualNumber);//add individualNumber into the vector
}
}
outputFile.close();
}
else
{
std::cout<<"input file cannot be openede"<<std::endl;
}
inputFile.close();
//print out the vector
for(int elem: vec)
{
std::cout<<elem<<std::endl;
}
return 0;
}
The output of the above program can be seen here.

Answer 2

Read from file to numbers using inputFile >> numbers. Then, add each digit character of the string to a std::vector.
Also, to write to the file, write each element of vector in a for loop.
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <sstream>
using namespace std;
int main()
{
char matrikelnummer[100];
cout << "Enter file name: \n";
cin >> matrikelnummer;
// Declare input file stream variable
ifstream inputFile(matrikelnummer);
string numbers;
vector<int> individualNumbers;
//Check if exists and then open the file
if (inputFile.good()) {
inputFile >> numbers;
for (int i = 0; i < numbers.length(); i++) {
if (numbers[i] >= '0' && numbers[i] <= '9')
individualNumbers.push_back(numbers[i] - '0');
}
// Close the file
inputFile.close();
}
else // In case TXT file does not exist
{
cout << "Error! This file does not exist.";
exit(0);
return 0;
}
// Writing solutions into TXT file called Matrikelnummer_solution.txt
ofstream myFile;
myFile.open("Matrikelnummer_solution.txt");
myFile << "Matrikelnummer: ";
for (int number : individualNumbers) {
myFile << number << " ";
}
myFile << endl;
myFile.close();
return 0;
}