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How to Read File Bytes into a Char Array in C++ Without getline()?

Published on 2024-11-08
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How to Read File Bytes into a Char Array in C   Without getline()?

How to Retrieve File Bytes into a Char Array in C

To read file bytes into a char array without using getline(), consider using ifstream::read(). Follow these steps:

  1. Open the File:

    std::ifstream infile("C:\\MyFile.csv");
  2. Get File Length:

    infile.seekg(0, std::ios::end);
    size_t length = infile.tellg();
    infile.seekg(0, std::ios::beg);
  3. Ensure Buffer Size:

    if (length > sizeof (buffer)) {
     length = sizeof (buffer);
    }
  4. Read the File:

    infile.read(buffer, length);

Additional Notes:

  • Opening the file in binary mode (e.g., with std::ios_base::binary) is recommended for accurate byte handling.
  • While seekg() and tellg() are generally reliable, they may not always provide exact file size in some cases.
  • For reading the entire file in one operation and handling large files, using std::vector and std::istreambuf_iterator may offer more flexibility.

Updated Approach (2019):

To account for potential errors during reading, consider the following approach:

size_t chars_read;

if (!(infile.read(buffer, sizeof(buffer)))) {
    if (!infile.eof()) {
        // Handle error during reading
    }
}

chars_read = infile.gcount(); // Get actual number of bytes read
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