Step by Step solution about How to resolve the algorithm Truncate a file step by step in the C++ programming language

The provided C++ code is a function called truncateFile that takes a filename and a maximum size as input and truncates the file to the specified size.

Explanation of the Code:

1. Header Inclusions:

   • The code includes necessary header files:
     • <string> for string handling
     • <fstream> for file handling

2. Function Definition (truncateFile):

   • The truncateFile function takes two parameters:
     • filename: The name of the file to truncate
     • max_size: The maximum size to which the file should be truncated

3. Input File Handling:

   • An input file stream (input) is created to read the contents of the original file (filename).
   • The input stream is opened in binary mode using std::ios::binary.

4. Output File Handling:

   • A new filename is generated by appending ".trunc" to the original filename (outfile).
   • An output file stream (appendFile) is created to write the truncated contents to the new file.
   • The output file is opened in append mode using ios_base::out.

5. Truncating the File:

   • A loop runs for a maximum of max_size iterations to control the truncation.
   • In each iteration:
     • A single character is read from the input file into the buffer variable.
     • The character is written to the output file using appendFile.

6. Closing File Streams:

   • After truncation, both input and output file streams are closed to release system resources.

7. Main Function:

   • The main function calls the truncateFile function with "test.txt" as the filename and 5 as the maximum size. This truncates the test.txt file to contain only the first 5 characters from the original file.

#include <string>
#include <fstream>

using namespace std;

void truncateFile(string filename, int max_size) {
  std::ifstream input( filename, std::ios::binary );
  char buffer;
  string outfile = filename + ".trunc";
  ofstream appendFile(outfile, ios_base::out);
  for(int i=0; i<max_size; i++) {
    input.read( &buffer, sizeof(buffer) );
    appendFile.write(&buffer,1);
  }
  appendFile.close();                                                                                                                                                                }

int main () {
  truncateFile("test.txt", 5);
  return 0;
}