Writing to a file in C++

Question

I'm trying to make a program that will get the user input of a new file name, create the file, and write to it. It works but it will only write the first word of the string to the file. How can i get it to write the full string? thanks.

#include "stdafx.h" #include <fstream> #include <iostream> #include <string> using namespace std; int main() { for (;;) { char *myFile = " "; string f = " "; string w = " "; cout <<"What is the name of the file you would like to write to? " <<endl; cin >>f; ofstream myStream(f,ios_base::ate|ios_base::out); cout <<"What would you like to write to " <<f <<" ? "; cin >>w; myStream <<w; if (myStream.bad()) { myStream <<"A serious error has occured."; myStream.close(); break; } } }

Community · Accepted Answer · 2017-05-23 11:46:43Z

According to this post, you should consult this reference to use a method like getline().

Also, when you are writing out I recommend that you flush the output (cout.flush()) before ending the program, especially in this case, since I presume you are ending the program with a ctrl-C break.

In formulating a suggestion, I will read data into char*, and convert them to "string" in case you will use them elsewhere in your program.

I tested this code in MS Visual C++ Express.

#include "stdafx.h" #include <fstream> #include <iostream> #include <string> using namespace std; int main() { for (;;) { char *myFile = new char[200]; // modified this line //added this line char *myInput = new char[200]; string f = " "; string w = " "; cout << "What is the name of the file you would like to write to? " << endl; cin.getline(myFile, 200);//modified this line f = (myFile);//added this line cin.clear(); //added this line ofstream myStream(f, ios_base::ate | ios_base::out); cout << "What would you like to write to " << f << " ? "; cin.getline(myInput, 200);//edited this line w = string(myInput);//added this line myStream << w; myStream.flush();//added this line if (myStream.bad()) { myStream << "A serious error has occured."; myStream.close(); break; } delete myFile; delete myInput; } }

David G · Accepted Answer · 2014-02-10 03:20:23Z

You have to use std::getline() to read the entire line:

std::getline(std::cin >> std::ws, w);

The >> std::ws part gets rid of leading whitespace which is needed because the newline left in the stream from the previous extraction will prevent std::getline() from fully consuming the input.

When inserting data into the stream you need to make sure it gets flushed (because, as the other answer said, you're probably using Ctrl+C to terminate the program and you may not see output during the program run). You can use the std::flush manipulator to flush the output:

myStream << w << std::flush;

DamnnnSure · Accepted Answer · 2014-02-10 03:33:03Z

cin<<w; cin would stop consuming input character when it encounter whitespace tab and other unseeable characters.

you should probably use std::getline() instead. take a look at this page for ref. http://en.cppreference.com/w/cpp/string/basic_string/getline

Or you can use manipulator to not skip whitespace.

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