C++ passing a file to a string [closed] - c++

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Hi i am trying to pass a whole file into a string. This is my Code but the program is always exiting on the first if(). I just can't get behind what i am doing wrong here.
#include <iostream>
#include <fstream>
#include <string>
std::string readFile (std::string filename);
int main() {
std::string filename;
std::string Eingabestring;
std::cout << "Geben Sie eine Datei an" << std::endl;
std::cin >> filename;
Eingabestring = readFile(filename);
std::cout << Eingabestring << std::endl;
return 0;
}
std::string readFile (std::string filename)
{
std::string zeile,inhalt ;
std::ifstream quelle;
quelle.open(filename.c_str());
if (!quelle)
{
std::cerr << filename << " kann nicht geöffnet werden!\n";
return exit(-1);
}
while (!quelle.eof())
{
getline(quelle,zeile);
inhalt = inhalt + zeile;
}
return inhalt;
}
Already thanks for your help!
Edit: I just noticed that i put the file into a wrong folder.. But the code still isn't reading the whole file. Just the first line, but i thought with the loop i could get every line of my file into the string?
And i fixed the second return 0 to exit(-1). Thats better right?

Answer 1

Other than checking to see why the open() failed as explained in the comments also keep in mind that there are easier ways to check for when you have hit the end of file in a while loop where you are reading from an istream.
The idiomatic way to loop and read from an istream in C++ is to embed the read expression that returns a reference to the istream in the loop condition, so change your code to
#include <iostream>
#include <string>
using std::cin;
using std::cout;
using std::endl;
using std::string;
int main() {
auto character = char{};
auto file_string = string{};
while (cin.get(character)) {
file_string += character;
}
cout << file_string << endl;
return 0;
}
I've used cin above but just replace cin with your file stream object and everything should work normally.
Note that the while terminating condition is now an istream reference, and that is convertible to bool, so the loop will exit when the istream object is done reading or when the stream encounters any errors besides EOF. You don't have to check for eof() yourself.
Also another thing is to pass strings that you do not intend to modify by const reference instead of by value, so the readFile() function should accept a const string& instead of a string, this will help save you string copying. When C++17 is available replace that const string& with std::string_view

Answer 2

Try something like this to read your file instead:
std::string readFile (std::string filename)
{
std::ifstream quelle(filename);
std::string content( (std::istreambuf_iterator<char>(quelle) ),
(std::istreambuf_iterator<char>()) );
return content;
}