C++ Files C-PLUS-PLUS
- C++ Introduction
- C++ Syntax
- C++ Output (cout <<)
- C++ Comments
- C++ Variables
- C++ User Input
- C++ Data Types
- C++ Operators
- C++ Strings
- C++ Math
- C++ Booleans
- C++ If Else
- C++ Switch
- C++ While Loop
- C++ Do/While Loop
- C++ For Loop
- C++ Break and Continue
- C++ Arrays
- C++ References
- C++ Pointers
- C++ Functions
- C++ Functions Parameters
- C++ Function Overloading
- C++ OOP
- C++ Classes and Objects
- C++ Class Methods
- C++ Constructors
- Destructors in C++
- C++ Access Specifiers
- C++ Encapsulation
- C++ Inheritance
- C++ Polymorphism
- C++ Files
- C++ Exception Handling
C++ Files
C++ Files
The fstream library allows us to work with files.
To use the fstream library, including both the standard <iostream> AND the <fstream> header file:
Example
#include <fstream>
There are three objects included in the fstream library, which is used to create, write or read files:
| Object/Data Type | Description |
|---|---|
ofstream |
Creates and writes to files |
ifstream |
Reads from files |
fstream |
A combination of ofstream and ifstream: creates, reads, and writes to files |
How to Create and Write To a File in C++
To create a file, use either the ofstream or fstream object, and specify the name of the file.
To write to the file, use the insertion operator (<<).
Example
#include <iostream>
#include <fstream>
using namespace std;
int main() {
// Create and open a text file
ofstream MyFile("filename.txt");
// Write to the file
MyFile << "Files can be tricky, but it is fun enough!";
// Close the file
MyFile.close();
}
How to Read a File in C++
To read from a file, use either the ifstream or fstream object, and the name of the file.
Note that we also use a while loop together with the getline() function (which belongs to the ifstream object) to read the file line by line, and to print the content of the file.
Example
#include <iostream>
#include <fstream>
using namespace std;int main () {
// Create a text file
ofstream MyWriteFile("filename.txt");// Write to the file
MyWriteFile << "Files can be tricky, but it is fun enough!";
// Close the file
MyWriteFile.close();// Create a text string, which is used to output the text file
string myText;// Read from the text file
ifstream MyReadFile("filename.txt");// Use a while loop together with the getline() function to read the file line by line
while (getline (MyReadFile, myText)) {
// Output the text from the file
cout << myText;
}// Close the file
MyReadFile.close();
}
Output:
Files can be tricky, but it is fun enough!
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