The get_next_line function reads data from a file descriptor, returning one line at a time. It is designed to handle text files or streams where lines are delimited by newline (\n) characters. The function retains state between calls, enabling successive retrieval of lines from the same file descriptor.

• Line-by-Line Reading: Processes files or streams one line at a time for efficient parsing.
• Buffer Management: Utilizes a buffer to optimize reading performance.
• Handles Large Files: Capable of reading large files without loading them entirely into memory.
• Works with Multiple File Descriptors: Can simultaneously read from multiple file descriptors.

char *get_next_line(int fd);

• fd (int): The file descriptor to read from.

• Returns a dynamically allocated string containing the next line, including the newline character (\n), if present.
• Returns NULL when:
  • The end of the file is reached.
  • An error occurs (e.g., invalid file descriptor or memory allocation failure).

1. Include the header file in your source code:

   #include "get_next_line.h"

2. Call the function in a loop to read lines until the end of the file:

int fd = open("example.txt", O_RDONLY);
if (fd < 0)
  return (1);

char *line;
while ((line = get_next_line(fd)) != NULL)
{
  printf("%s", line);
  free(line);
}
close(fd);

Ensure the following files are included in your project:

• get_next_line.c
• get_next_line_utils.c
• get_next_line.h

Compile using gcc or your preferred compiler:

gcc -Wall -Wextra -Werror -D BUFFER_SIZE=42 get_next_line.c get_next_line_utils.c -o get_next_line

Replace BUFFER_SIZE with your desired buffer size.

• Memory Management: Each call to get_next_line returns a dynamically allocated string. The caller must free the memory to prevent leaks.
• Buffer Size: The BUFFER_SIZE macro must be defined during compilation. Its value significantly affects performance and memory usage.

• The function relies on the presence of \n to delimit lines. If the file does not end with a newline, the final line will still be returned.
• The behavior for non-text files (e.g., binary data) is undefined.

Given the file example.txt:

Hello, World!
This is a test.
EOF.

Hello, World!
This is a test.
EOF.

Developed by Iammar as part of the 1337 School (42 Network) project for mastering file I/O and dynamic memory allocation in C.