Line by Line or All at Once: Which is the Best Way to Read Text Files in C ?

Reading Text Files: Line by Line vs. At Once

In a programming context, encountering text files can present challenges like reading their contents efficiently. This article aims to provide guidance on understanding how to read text files either by iterating through each line or by loading the entire text into memory in one operation.

Reading Line by Line

The provided code demonstrates how to read a text file word by word. To read the file line by line, we utilize the std::getline function, which retrieves each line as a string. The code below showcases this approach:

#include <fstream>
#include <string>

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

Reading the Entire Text File at Once

Alternatively, to read the entire file at once, we concatenate the retrieved lines into a single string. The code below exemplifies this technique:

#include <fstream>
#include <string>

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

Choice of Approach

The appropriate choice of reading method depends on the specific requirements. Reading line by line is suitable when processing individual lines is necessary. Reading the entire file at once is more efficient when the entire text is required for further processing.

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