Member Avatar for ananthu

i need to read contents of a file(of any format) into a char array, how can i do this

  • 2 Contributors
  • 1 Reply
  • 462 Views
  • 6 Hours Discussion Span
  • Latest Post Latest Post by JerryShaw

Dani AI

Generated

For : decide first whether you need raw bytes (an exact copy of the file) or decoded text (characters interpreted using an encoding). A char buffer in C++ can hold raw bytes from any file; interpreting those bytes as characters is a separate step and depends on the file encoding (UTF‑8, UTF‑16, etc.).

A simple, robust pattern to read the whole file as bytes (safe for binary files) uses RAII and avoids manual delete:

#include <fstream>
#include <vector>
#include <stdexcept>

std::vector<char> readFileBytes(const std::string& path) {
    std::ifstream in(path, std::ios::binary | std::ios::ate);
    if (!in) throw std::runtime_error("open failed");
    std::streamsize size = in.tellg();
    if (size < 0) throw std::runtime_error("could not determine size");
    in.seekg(0, std::ios::beg);
    std::vector<char> buf(static_cast<size_t>(size));
    if (!in.read(buf.data(), size)) throw std::runtime_error("read failed");
    return buf;
}

If you specifically want a C-style char[] (null-terminated), either use std::vector<char> and push_back('\0'), or allocate new char[size+1] and set the final byte to '\0'. For text files, reading into a std::string via std::ostringstream or istreambuf_iterator is convenient and keeps the data as characters ready for string operations.

Practical tips: always open in std::ios::binary for non-text files; check that tellg() returned a valid size; use chunked reads or memory-mapping for very large files; prefer std::vector<char>/std::string to manual new[] to avoid leaks. As pointed out, remember to release resources and be explicit about encoding when you need characters rather than raw bytes.

Member Avatar for JerryShaw

i need to read contents of a file(of any format) into a char array, how can i do this

FileInfo fz = new FileInfo(tempFile);
FileStream fzs = fz.Open(FileMode.Open, FileAccess.Read, FileShare.Read);
byte[] data = new byte[fz.Length];
fzs.Position = 0;
fzs.Read(data, 0, Convert.ToInt32(fz.Length));
string strData = Encoding.UTF8.GetString(data);
char[] ch = strData.ToCharArray();

Remember to dispose, and try..catch, all that stuff.
Basically you stream the file, read the stream into a byte array, then encode the byte array into a string where you can turn it into a char array. You may need to try differenent encoding depending on culture settings, etc.

Jerry


Just thought of a one liner that also does this: (if it is a text file you are working with)

char[] ch = File.ReadAllText("filename.txt").ToCharArray();
Edited by JerryShaw because: added content
Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.