How Can I Efficiently Read Lines and Entire Files in C ?

Reading Lines and Files in C

As you mentioned in your query, reading files line by line or in its entirety is more efficient than processing them word by word, especially for large files. Here's a detailed explanation of how to achieve both scenarios:

Reading Line by Line:

To read a file line by line, you can utilize the std::getline function. Here's an example:

#include <fstream>
#include <string>

int main() 
{ 
    std::ifstream file("Read.txt");
    std::string line; 
    while (std::getline(file, line))
    {
        // Process each line here
    }
}

This code snippet opens the file named "Read.txt" and reads each line stored in the line string. You can then process the individual lines as needed.

Reading the Entire File at Once:

To read the entire file contents at once, you can concatenate the lines into a single string. Here's a modified version of the previous code:

std::ifstream file("Read.txt");
std::string line;
std::string file_contents;
while (std::getline(file, line))
{
  file_contents += line;
  file_contents.push_back('\n');
} 

This code reads each line and appends it to the file_contents string, including a newline character to preserve the original line breaks. The final file_contents string will contain the entire file contents.

Note that it's generally recommended to use the ifstream constructor to open the file with its filename rather than using the open method, and to rely on the destructor to automatically close the file.

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