File Splitter in C

A minimal command-line file splitter written in C.

The program reads a file in fixed-size memory blocks, splits the file into multiple smaller parts, and writes each part into separate output files.

This project focuses on learning low-level file I/O, memory management, buffers, and command-line argument handling in C.

Tutorial: Video Tutorial Available (by Daniel Hirsch)

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Features

• Split files into multiple parts
• Works with large files
• Uses buffered file reading/writing
• Simple CLI interface
• Uses low-level C file operations
• Dynamically allocates memory using malloc()

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How It Works

• Reads command-line arguments for filename and number of splits
• Opens the input file using fopen()
• Determines file size using fseek() and ftell()
• Calculates:
  • part size
  • remaining bytes
• Allocates a temporary memory buffer using malloc()
• Reads chunks from the source file using fread()
• Writes chunks into split files using fwrite()
• Generates output files using:
  • filename-part0
  • filename-part1
  • etc.

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Build

Compile using:

gcc -Wall -Wextra -g -o filesplitter filesplitter.c

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Usage

Run:

./filesplitter <filename> <num_splits>

Example:

./filesplitter movie.mp4 4

This creates:

movie.mp4-part0
movie.mp4-part1
movie.mp4-part2
movie.mp4-part3

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Example

Input:

movie.mp4 (1 GB)

Command:

./splitter movie.mp4 5

Output:

movie.mp4-part0
movie.mp4-part1
movie.mp4-part2
movie.mp4-part3
movie.mp4-part4

Each part contains approximately equal portions of the original file.

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Notes

• The program processes files using a fixed buffer size (BLOCK_SIZE)
• Remaining bytes are added to the final split file
• Output files are generated by appending:

-part<number>

to the original filename

• Large files may take time depending on disk speed

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Concepts Practiced

• File handling in C
• fopen()
• fseek()
• ftell()
• fread()
• fwrite()
• Dynamic memory allocation
• Pointers
• Buffers
• Command-line arguments
• Binary file processing

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Future Improvements

• Merge split files back together
• Progress bar support
• Configurable buffer size
• Better error handling
• Support for extremely large files
• Multi-threaded splitting