C++ Program to Read File Line by Line

C++ Read File Line by Line

In C++ we can read files Line by Line by two methods. The first is to read the line token by token and the second is Line based on parsing, which is done using string streams that we get using the std::getline() Function.

std::getline() Function from a given string to read the content line by line into a std::string and later process them.

C++ Read File Line by Line Using std:: getline() Function

In C++, reading a file line by line is best done with the getline() function. When the delimiter char is reached, the function reads characters from the input stream and puts them in a string. The third optional element is the delimiter, which by default is taken to be the new line character \ns.

Syntax of std:: getline() Function

Here,

• is: It informs the method about the stream it should read input from and is an object of the stream class.
• str: The input is read from the stream and stored in this object, which is a string.
• delim: The function is instructed to cease reading more input when it reaches this character (provided by the user in the getline() function). It is optional.

Algorithm

• Begin
• Make an object to type a new file with the fstream class.
• To perform a write operation using the object newfile, call the open() function to open the xyz.txt file.
  • If the file is open, then
    • In the xyz.txt file, type the string My Function".
    • Utilizing the close() method, close the file object newfile.
  • To execute a read operation using object newfile, call the open() function to open the xyz.txt file.
  • If the file is open, then
    • Declare a string sa.
    • Using the getline() method, read the entire data of the file object newfile, and then put it into the string sa.
    • Print the data of string sa.
• Utilizing the close() method, close the file object newfile.
• End.

Code Implementation

Output

Explanation

In the above code, we have first created an object new_file using the steam class. After that the file we have created we will open it and add some content to it and then close the file using the close() method.

After that, we will again open the file and create a string sa and then using the getline() function, we will read the entire file line by line and put the data into the string. After that, we printed the data, and at last, we closed the file.

Examples

Let's take an example to understand to concept of the getline() function.

Output

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